Reply To: Need help on first dwarf tank

Pete Giwojna

Dear Richard:

In general, the setup for dwarf seahorses that you are considering is quite sensible. But if you want to use a few pieces of live rock, you’ll need to do without the featherduster and brittle starfish since you will need to pre-treat your live rock with fenbendazole (brand name Panacur) in order to prevent hydroids, and the fenbendazole will kill featherduster worms and could be harmful to the starfish. If you’ll be using a simple sponge filter — which is an excellent idea – then a bare glass bottom for your substrate is just fine.

Okay, I would be happy to provide you with some suggestions and additional information and articles on keeping dwarf seahorses (Hippocampus zosterae), Richard.

I usually start out with a standard All Glass Aquarium (now known as Aqueon Aquariums) of anywhere from 5-10 gallons – depending on how many dwarves I will be keeping (as you know, they are colonial seahorses that do best in groups) – and then equip it with a simple set of air-operated undergravel filters or air-operated sponge filters.

Of course, you can keep dwarf seahorses using more sophisticated hang-on-the-back power filters as well, Richard, but the more sophisticated filtration system, the more creative and inventive you have to get in order to assure that the filter won’t produce water currents that are too overpowering for the tiny dwarf seahorses or that won’t whisk their food past them too fast to target and eat, and to assure that the intake for the filter will not suck up and remove all of the newly hatched brine shrimp or other live foods you are providing for the tour seahorses before the ponies get much of a chance at it. In other words, power filters require a lot of modifications to make them suitable for use on a dwarf seahorse tank. (On the other hand, both the simple air-operated undergravel filters and basic air-operated sponge filters provide efficient biological filtration and are completely safe to use for your seahorses as is with no modification whatsoever.)

So when I am setting up a dwarf seahorse tank, Richard, I tend to keep it simple and stick with foolproof UG’s or sponge filters, and then I supplement the filtration using well-cured live rock (or man-made live rock that has been colonized by beneficial nitrifying and denitrifying bacteria).

Live rock is normally taboo in a dwarf seahorse tank because it quickly leads to problems with Aiptasia rock anemones and hydroids, which thrive on the constant supply of newly hatched brine shrimp or similar live foods, and which are deadly to the dwarves. But you can turn that to your advantage simply by treating the tank with low doses of fenbendazole (brand name Panacur), which kill Aiptasia rock anemones, hydroids, and bristleworms of all kinds. The porous live rock will absorb some of the fenbendazole and then leach it back into the tank at very low levels for many months thereafter, quite effectively keeping the aquarium free of rock anemones, hydroids, and bristleworms without being harmful to the adult dwarf seahorses or their newborns in any way.

Here is some more information on this technique for keeping live rock and live sand safely the seahorses that you may find helpful, Richard:

As you know, most dwarf seahorse keepers will avoid live rock and live sand in order to reduce the risk of hydroids getting started in their aquarium, but there are ways around that that actually turned the live rock into an advantage for preventing hydroids, as we’ll discuss in more detail below.

Live rock and live sand are excellent for supplemental filtration and adding stability to a dwarf seahorse tank, but it also means that you are going to have chronic problems with hydroids and Aiptasia rock anemones unless you take special precautions to control them, which is actually easy to accomplish.

Sooner or later hydroids will appear in any marine aquarium that is receiving regular feedings of rotifers, copepods, or baby brine shrimp. It’s inevitable because they can gain entry into the aquarium in many ways. For example, they are notorious hitchhikers. Both the colonial polyp stage and the free-swimming micro-jellies can thumb a ride on live rock, macroalgae, hitching posts, sand or gravel, specimens of all kinds, or within so much as a single drop of natural seawater (Abbott, 2003). Beware of fuzzy looking seashells! Very often hydrozoans come in on the shells of the hermit crabs or snails we purchase as aquarium janitors (Abbott, 2003). Or they may be introduced with live foods, or even among Artemia cysts, in some cases it seems. They can even be transferred from tank to tank in the aerosol mist arising from an airstone or the bubble stream of a protein skimmer.

So with the live rock and live sand, you’re going to have an ongoing problem with hydroids and likely also app Aiptasia rock anemones in your dwarf setup, and that’s a cause for concern. Because of their diminutive dimensions, dwarf seahorses are susceptible to the stings from hydroids and Aiptasia rock anemones. Hydroids in particular are especially problematic for dwarves because once they find their way into a dwarf seahorse setup or nursery tank, the dreaded droids can explode to plague proportions very quickly because conditions are ideal for their growth: perfect temperatures, an abundance of planktonic prey that is renewed every few hours, and a complete absence of predators. As they proliferate and spread, they will soon begin to take a toll on the seahorse fry and even adult dwarfs can succumb to multiple stings or secondary infections that can set in at the site of a sting (Abbott, 2003).

But there is a way you can turn this situation to your advantage and eliminate the risk of hydroids, app Aiptasia rock anemones, and bristleworms from your dwarf seahorse tank, Richard. Treating your dwarf tank with a regimen of fenbendazole will eradicate these pests and provide long-lasting protection from hydroids and Aiptasia for your dwarf seahorses. Allow me to explain.

Eliminating Hydroids

Hydroids can be controlled in the aquarium by using a medication known as fenbendazole to treat the tank over a period of days. Fenbendazole (brand name Panacur) is an inexpensive anthelmintic agent (dewormer) used for large animals such as horses, and the de-worming granules can be obtained without a prescription from stores that carry agricultural products (e.g., farm and ranch equipment, farming supplies and products, veterinary supplies, livestock and horse supplies, livestock and horse feed). If you live in a rural area, those would be good places to obtain it as well.

However, there are a couple of things you should keep in mind when treating an aquarium with fenbendazole, Richard. Administering a regimen of fenbendazole (FBZ) or Panacur will eradicate any hydroids, Aiptasia rock anemones, or bristleworms from live rock or live sand, thereby rendering them completely seahorse safe. The recommended dose is 1/8 teaspoon of the horse dewormer granules (22.2% fenbendazole) per 10 gallons of water. Dose aquarium with 1/8 teaspoon/10 gallons every other day until you have administered a total of 3 such treatments (Liisa Coit, pers. com.). Even one dose will do a fine job of eradicating bristeworms, but Aiptasia rock anemones and hydroids are a bit tougher and may require 2-3 doses to eliminate entirely.

Because fenbendazole is essentially a de-worming agent, it will destroy any bristleworms, flat worms, spaghetti worms or the like. Fenbendazole does not have any adverse effects on biological filtration, but be aware that it is death to many Cnidarians besides hydroids. Mushrooms and related corals are generally not affected, but expect it to have dire effects on other corals (e.g., sinularias), polyps, gorgonians, and anemones. In general, any Cnidarians with polyps that resemble the stalked family of Hydrozoans are likely to be hit hard by fenbendazole, so don’t use this treatment in a reef tank! Dwarf seahorse keepers, of course, don’t keep alive corals so this is not a disadvantage for a dwarf seahorse tank at all.

Also be aware that fenbendazole seems to soak into the porous live rock and be absorbed indefinitely. I know one hobbyist who transferred a small piece of live rock that had been treated with fenbendazole (Panacur) months earlier into a reef tank, where it killed the resident starfish and Astrea snails. So enough of the medication may be retained within treated live rock to impact sensitive animals months after the fenbendazole was administered. Don’t treat live rock intended for reef systems with fenbendazole (Panacur)!

At the lower dosage recommended for nursery tanks and dwarf seahorse tanks with fry (1/16 tsp. per 10 gallons), fenbendazole normally does not harm cleaner shrimp and decorative shrimp. With the exception of Astrids (Astrea), Coit and Worden have found it does not usually affect the types of snails typically used as cleanup crews (e.g., Nassarius, Ceriths, and Nerites). It will kill starfish but copepods, hermit crabs, and shrimp are normally not affected.

Macroalgae such as the feathery or long-bladed varieties of Caulerpa or Hawaiian Ogo (Gracilaria) are not harmed by exposure to fenbendazole at even triple the normal dose. In fact, if you will be using Caulerpa in your nursery tanks to provide hitching posts for the fry and serve as a form of natural filtration, it’s a very wise precaution indeed to treat them with a regimen of fenbendazole beforehand.

So fenbendazole (FBZ) or Panacur is primarily useful for ridding bare-bottomed nursery tanks and dwarf seahorses setups of hyrdroids and Aiptasia anemones, ridding Caulerpa and other macroalge of hydroids or Aiptasia before its goes into the aquarium, and cleansing live rock of bristleworms, hydroids, and Aiptasia rock anemones before it is introduced to the aquarium.

It can also be used to eradicate bristleworms, hydroids, an Aiptasia from an established aquarium if it does not house sensitive animals such as live corals and gorgonians, starfish, Astrea snails, or tubeworms and other desirable worms that may be harmed by FBZ, providing you monitor the ammonia levels closely and are prepared to deal with the ammonia spike that may result from the sudden death of the worm population.

Live rock and live sand that has been pretreated with fenbendazole should be quite safe for dwarf seahorses and their fry, and because it soaks into the porous interior of the live rock and then is gradually released again, it can provide a dwarf seahorse tank with long-lasting protection against stinging organisms like hydroid’s and app Aiptasia rock anemones. The amount of the fenbendazole that gradually leaches out of the porous live rock is quite miniscule. It is effective in controlling hydroids and various marine worms even in the insignificant dosage that seeps out of the treated LR because they are sensitive to the medication and even though the dose of fenbendazole that is released is negligible, it is being released at a fairly constant rate and therefore maintaining a continuous, very low level of fenbendazole in the tank. Fenbendazole is an anthelminthic agent or dewormer, designed to kill certain invertebrates such as worms, and it is therefore deadly to bristleworms and cnidarians with nematocysts such as Aiptasia anemones and hydroids, but it is quite safe to use with vertebrates such as seahorses at the dosages we are discussing.

In short, even at relatively concentrated doses, fenbendazole does not harm seahorse fry when it is being used to eradicate hydroids from nursery tanks, so it should not be harmful to your dwarf seahorse fry in the insignificant amounts that gradually leach out of pretreated live rock. In fact, I know a couple of dwarf seahorse keepers who use pretreated live rock in their setups, and they have reported no problems with it affecting their H. zosterae fry. As long as there are no sensitive corals or Astrea snails in your dwarf seahorse tank, I don’t believe fenbendazole-treated live rock would pose any risk for your dwarf seahorses or their offspring, and I would recommend treating your dwarf tank with a regimen of fenbendazole as soon as possible.

In short, don’t hesitate to use live rock and live sand when you set up your dwarf seahorse tank, Richard, providing you are willing to treat the aquarium with Panacur in order to eliminate stinging animals such as hydroids, Aiptasia rock anemones, and bristleworms.

I usually get my granular fenbendazole (brand name Panacur) from KV Vet Supply. They use to sell it in small packets of 5.2 g as well as larger quantities and in the paste form. If that’s no longer the case, you can get fenbendazole granules in small quantities from the following vendor:

As you know, fenbendazole (i.e., Panacur) is an inexpensive anthelmintic agent (dewormer) used for large animals such as horses, and the de-worming granules can be obtained without a prescription from stores that carry agricultural products (e.g., farm and ranch equipment, farming supplies and products, veterinary supplies, livestock and horse supplies, livestock and horse feed). If you live in a rural area, those would be good places to obtain it as well.

The only drawback to this method – using live rock and live sand together with low doses of fenbendazole to eradicate dwarf seahorse pests – is that it also limits the type of tankmates you can include with your dwarf seahorses. For instance, you won’t be able to keep feather dusters, Fromia starfish, and certain snails in your dwarf tank if you’re using low doses of fenbendazole, but that’s a small place to pay to protect your dwarf ponies from hydroids and rock anemones, which are the number one reasons that most dwarf seahorse setups fail in the long run.

I’ll give you a lot of additional information on keeping dwarf seahorses that explains a number of other techniques favored by other hobbyists who fancy the diminutive dwarfs, Richard, and you can look over all of this material and then decide which of those methods might be best suited for your needs and interests.

For starters, here is the species summary on dwarf seahorses from my new book (Complete Guide to the Greater Seahorses in the Aquarium, unpublished), which discusses my preferred method (at that time) for keeping the dwarfs along with lots of other useful information.

Hippocampus zosterae (Tropical to Subtropical, Benthic)
Common name: Dwarf Seahorses, Sea Ponies, Pygmies or Pigmies, and Pixies (US).
Scientific name: Hippocampus zosterae Jordan & Gilbert, 1882
Hippocampus regulus
Hippocampus rosamondae
Maximum size: 2 inches (5.0 cm) in total length.
Climate: subtropical to tropical: 20° N to 30° N.
Western Atlantic: Bermuda, southern Florida, Bahamas and the entire Gulf of Mexico.
Meristic Counts:.
Rings: 9-10 trunk rings + 31-32 tail rings.
Dorsal fin rays: 12 soft rays spanning 2 trunk rings + 0 tail rings.
Pectoral fin rays: 11-12 soft rays.
Snout length: 4.2-4.3 in head length. In other words, the length of the snout will fit into the seahorse’s head length more than four times (i.e., they have very short, stubby snouts that are usually < 1/4 the length of their heads).
Other distinctive characters:
Coronet: high, columnar or knob-like, without spines or projections.
Spines: low or knob-like.
Cirri: variable — some have none, others are very shaggy due to profuse cirri.
Key Features: short snout (always <1/3 to 1/4 their head length).
Adult height: 3/4 inch to 1-3/4 inches (2 to 4-1/2 cm).
Color and Pattern:
Dwarf seahorses can be extremely variable in coloration. Their base coloration is typically beige or fawn, but may be dark brown, gray, or oyster shell white and colorful sports of every description occur occasionally. Their normal pattern is a mottled fawn color, but greenish, yellow, black, brown, and pearly specimens are fairly common, and saddles, blotches, ringed-tails, and pinto- and bumblebee-like patterns are seen from time to time (Giwojna 1990; Giwojna, Jun. 2002). Many specimens are marked with white flecks like splashes of paint and a dark sub-marginal stripe on the dorsal fin is a common feature.

Breeding Habits:
Breeding Season: mid-February to late October, as determined by day length.
Gestation Period: about 10 days, depending on temperature and diet.
Egg Diameter: 1.3 mm.
Brood Size: 5-55 fry; occasional large broods up to 70 fry have been reported, but two dozen fry is much more typical.
Size at Birth: 1/3 inch (7-9 mm)
Onset of sexual maturity: fry grow rapidly, reaching maturity after 2-3 months.
Pelagic/Demersal (benthic): benthic; newborns orient to the substrate and seek out hitching posts immediately after birth.

Ease of Rearing:
As easy as it gets. Many home hobbyists have closed the life cycle with this species and H. zosterae is widely considered to be the easiest of all seahorses to raise. Eminently well suited for the easy rearing method.

Natural Habitat:
H. zosterae is restricted to seagrass microhabitats in shallow water, and is typically found living in association with the seagrass Zostera (Bull and Mitchell, 2002, p56), for which the species is named.
Natural History:
The dwarf seahorse resides in shallow grass flats amidst Zostera and other seagrass and is also known for its rafting ability, commonly being found in mats of floating Sargassum. It occurs in the coastal Gulf of Mexico, Bahamas, Bermuda, the Florida Keys, Florida’s East Coast, Old Tampa Bay, Lemond Bay, Pensacola, and Texas (Bull and Mitchell, 2002, p56).
These tiny seahorses are tough as nails, a legacy of their shallow, inshore environment in which the water conditions typically range from 43 F to 98 F (6 C – 37 C) and from marine to brackish (40% fresh water) during the seasons. They tolerate extremes that would be fatal to most other fishes and can adapt to a wide range of temperatures and salinity in the aquarium, but they are most common in bays during periods of high salinity and prefer the specific gravity to be maintained in the low normal range (1.019-1.022). They are diurnal seahorse that are active by day, and their aquarium should be lighted at least 12 hours a day since their breeding season is determined by day length (they stop reproducing when there is less than 12 hours of daylight) (Strawn 1954).
H. zosterae has been well studied in the field and in the laboratory, and research has determined that the dwarf seahorse forms monogamous pairs in the wild that court early each morning until mating occurs (Masonjones and Lewis 1996). Four distinct phases of courtship precede pair formation and mating (Masonjones and Lewis 1996). The first phase of courtship lasts for one or two mornings prior to the actual mating and consists of repeated bouts of reciprocal quivering in which the male and female brighten and alternately engage in a series of rapid (12 cycles per second) side-to-side body vibrations (Masonjones and Lewis 1996). When one of the seahorses stops quivering, its partner must pick up where it left off and resume shimmying within 5 seconds (Masonjones and Lewis 1996). Back and forth, the pair will exchange repeated series of quivering throughout the morning of the first day(s) of courtship.
The remaining 3 phases consist of new behaviors that all appear during the final day of courtship and build up inexorably to the grand finale. In the second phase, the female begins to Point and the male responds with displays of Pumping (Masonjones and Lewis 1996). In the third phase, the male begins to echo the female’s Points by Pointing in return (Masonjones and Lewis 1996). And in the final phase of courtship, the pairs repeatedly rise together in the water column, eventually leading to a brief midwater coupling during which the females deposits her eggs in the male’s brood pouch (Masonjones and Lewis 1996).
One a pair has formed in this manner, the partners are believed to remain together and mate exclusively with each other throughout the breeding season in the wild (Masonjones and Lewis 1996). The female normally re-mates with the male 4-20 hours after he gives birth to his latest brood (Masonjones and Lewis 1996). Interestingly, although these miniature ponies are but a fraction the size of H. reidi, female dwarves produce eggs that are slightly larger (egg diameter is 1.3 mm) than the ova reidi mares produce (Lourie, Vincent & Hall 1999).
The breeding season extends from February to October, and the males deliver anywhere from 5 to 55 fry after a gestation period of just 10 days. Considering the tiny size of the males and the very short period of gestation, newborn H. zosterae are surprisingly large (7-9mm) and well developed (Bull and Mitchell, 2002, p56). They immediately orient to the bottom and seek out hitching posts, and are able to eat newly hatched brine shrimp (Artemia nauplii) right from birth. The young grow very rapidly, more than doubling in size after their first 17 days (Bull and Mitchell, 2002, p56), and within a mere 2-3 months they are already producing offspring of their own. When fully grown, they will only 1 inch to 1-3/4 inches (2.5-4.5 cm) long (Bull and Mitchell, 2002, p56).
This accelerated life cycle is necessary because dwarves have a very short life expectancy in the wild. Very few adults survive their first winter, and to my knowledge none of them have ever been known to overwinter twice (Strawn 1953, 1958). That makes their maximum lifespan about 1-1.5 years in their natural habitat. But they are amazingly resilient and these diminutive denizens of the deep cram a whole lot of living into that short period. In 85 F (30 C) water, a male will have at least two broods a month, with the young developing very quickly during the summer months and becoming sexual mature in only 2 to 3 months. That means a male that delivers his first brood in mid-February can easily produce a dozen broods or more during the breeding season, and may become a great-great-grandfather by the end of the season in October. Amazing animals!

Preferred Parameters:
Carol Cozzi-Schmarr recommends that Ocean Rider’s captive-bred-and-raised dwarf seahorses (H. zosterae) be maintained under the following conditions:
Temperature = range 68°F to 80°F (20°C-27°C), optimum 75°F (24°C).
Specific Gravity = range 1.018 – 1.024, optimum 1.019-1.022
pH = 8.2 – 8.4
Ammonia = 0
Nitrite = 0
Nitrate = 0-10 ppm
Suggested Stocking Density: 2 pairs per 1 gallon (4 liters).

Aquarium Requirements:

Because of their small size, dwarf seahorses are best suited for a small aquarium of 5-10 gallons (19-38 liters). The water quality parameters should be as described above.

I prefer a very basic setup for keeping dwarf seahorses (Hippocampus zosterae). Depending on the size of my herd, I like anything from a standard 2-1/2 gallon to a 10-gallon tank (all glass construction, of course — no stainless steel), equipped with a glass top and an ordinary strip reflector.

Regardless of the size of my dwarf tank, I like to encourage green algae to grow on back and side panels of the aquarium, although I use an algae scraper to keep the front viewing glass scrupulously clean. Newly hatched brine shrimp (Artemia nauplii) like to feed on the green algae, which attracts the attention of the dwarf seahorses who in turn feed on the baby brine shrimp. In addition, the microalgae on the glass helps to keep the nitrates in the aquarium will.

For filtration, I keep things really simple, using only air-operated sponge filters or a well-maintained undergravel filter that covers the bottom of the tank completely on dwarf tanks. I know undergravels are considered old-fashioned technology nowadays, but they are inexpensive, utterly reliable and foolproof (no moving parts), easy to install, and work extremely well for dwarf seahorses with no modification whatsoever. An inexpensive diaphragm air pump will operate the filter and provide all the aeration you need.

Sponge or foam filters provide all the same advantages of undergravels and more. So in actual practice, I normally prefer foam filters over undergravels for smaller dwarf tanks, simply because the foam filters are easier to clean and maintain, and are quite a bit more versatile than the undergravels.

Avoid sponge filters with weighted bottoms or other metal components, however, since they will rust when exposed to saltwater. Sooner or later this will cause problems in a marine aquarium (sooner in the small setups that are most suitable for H. zosterae). Select a sponge filter that has no metal parts and is safe for use in saltwater. The proper units will have suction cups to anchor them in place rather than a weighted bottom.

Cleaning the foam filters is a snap. Simply immerse them in a bucket of saltwater and gently squeeze out the sponge until it’s clean and releases no more sediment or debris. Run a bottlebrush through the inside of the tube, wipe off the outside of the tube, and you’re done. The filter is ready to go back in the aquarium with no impairment at all of the biofiltration. Takes only a couple minutes.

I like to keep a few extra sponge filters running in my sump or a refugium at all times. That way, I’ve got instant, fully established, portable biofilters I can use wherever needed — a hospital ward or quarantine tank, a nursery tank or rearing tank, a brand new setup, or anytime the biofiltration needs a boost in another tank for any reason. Very versatile! You’ll never realize how valuable an instant biofilter can be until you really need one.

I find sponge filters and undergravels are generally the best option for dwarf seahorses because most other types of filtration aren’t practical in such small setups. Power filters would turn a 2-1/2 or 5 gallon tank into a maelstrom, battering pigmy ponies around. And power filters have a bad habit of “eating” dwarf seahorses and filtering out all the Artemia nauplii before the seahorses can make a dent in it.

I still use rock in my larger dwarf setups, but it’s “dead” foundation rock instead of live rock. This dead or dry foundation rock is considerably cheaper than live rock and is, of course, completely free of undesirable pests and unwanted hitchhikers. But it will quickly enough becomes alive once it’s placed in the aquarium as it’s overgrown by algae and inhabited by copepods, amphipods and myriad microfauna. And over time the porous dead/foundation rock will become inhabited by a thriving population of nitrifying bacteria, giving it biofiltration ability. Eventually the oxygen-deprived interior of the “dead” rock will be populated by aerobic denitrifying bacteria, which convert nitrate to nitrogen gas, thereby helping to keep the nitrate levels in the aquarium under control.

By this point, the foundation rock will be very much alive and can provide all the benefits of live rock with none of the risks. The inert foundation rock looks completely natural when surrounded by living, growing macroalgae, especially when it becomes encrusted by microalgae or coralline algae, as the case may be.

The drawback to this approach is that it takes considerably longer for a new marine aquarium to cycle from scratch using dry rock than it does with live rock, and you must “seed” the tank with beneficial nitrifying bacteria from another clean source in order to start the cycling process. But the advantage of using dead foundation rock is the cheaper cost and, above all, the fact that it completely eliminates unwanted hitchhikers such as Aiptasia rock anemones, bristleworms, mantis shrimp, hydroids, and rock crabs. If they are patient, many home hobbyists feel the advantages outweigh the drawbacks.

One good source for such dry foundation rock is Macro Rocks, which offers dead, dried ocean rock in a number of interesting formations and a wide variety of types (Florida, Fiji, Tonga, etc.). They offer many beautiful, unique and intricate formations of dried ocean rock that would be an asset to any seahorse setup. Best of all, you can even purchase the Macro Rocks precycled and carrying a full complement of beneficial nitrifying bacteria, which allows you to cycle a new aquarium using the Macro Rocks as fast as an aquarium with live rock.

Macro Rocks are available online at the following website:

A lush bed of assorted Caulerpa dominates the rear third of my current dwarf tank, completely concealing the sponge filters. The Caulerpa consists of various long-bladed and plumed or feathery varieties such as Caulerpa sertularioides, Caulerpa mexicana, Caulerpa ashmedii, Caulerpa serrulata and Caulerpa prolifera. The center of the tank is aquascaped with more macros — mostly red and gold species of Gracilaria (Hawaiian Ogo), plus a seahorse tree centerpiece and yet more Caulerpa. Other decorative macros are arranged in the foreground of the aquarium where the light is brightest: a cluster of Merman’s Shaving Brushes (Penicillus capitatus) and a stand of Halimeda sea cactus, interspersed with Udotea palmate fans. The result is a colorful macroalgae garden with a very nice contrast of colors (reds, yellows, greens, and brown) and interesting shapes. A tank heavily planted with macros such as these is a lovely sight and mimics the dwarf seahorse’s natural seagrass habitat well.

As an added benefit, the macroalgae act as an excellent form of natural filtration, supplementing the sponge filters, and reducing the available levels of phosphates and nitrites/nitrates. When we prune and trim back the fast-growing Caulerpa regularly and remove the clippings, we’re actually exporting phosphates, nitrates and other nutrients from the tank, thereby helping to maintain good water quality.

For the substrate with sponge filters, I like a bed of fine grained black sand about 3/4-inch to 1-inch deep, both for it’s pleasing appearance and to accommodate Nassarius snails, which like to bury in the sand bed. The Nassarius snails are the cornerstones of the clean-up crew in my dwarf tanks. Nassarius snails are very active, efficient scavengers that handle the meatier leftovers and make a fine cleanup crew for a dwarf seahorse tank when combined with herbivorous snails such as Astrea and Cerith snails.

I do small weekly or biweekly water changes on my dwarf tanks of 10%-15%, rather than the monthly or bimonthly water changes I perform on large setups, but the volume of the water exchanged is so small — just a gallon or so at most — that they are a breeze. Heck, if I mix up a 5-gallon bucket of new artificial salt mix in advance, that provides enough clean, aged saltwater for a month’s worth of water changes on my dwarf tank. When I siphon out the water for the weekly exchanges, I use the opportunity to vacuum the substrate and tidy up the tank a bit. Once it settles, I use the water I siphoned out to clean the sponge filters. The whole process, water change and all, takes all of 10 minutes.

But that 10 minutes of weekly maintenance returns wonderful rewards in terms of water quality. With such a small volume of water, the conditions can deteriorate quickly in a dwarf tank, and this modicum of weekly maintenance keeps things running smooth and trouble free.

In short, my current dwarf seahorse setup is basically a 5-gallon tank equipped with two air-operated sponge filters for biological and mechanical filtration, plus lush beds of macroalgae for natural filtration, simulating the pigmy ponies’ seagrass habitat. This is a very simple, inexpensive, low-maintenance aquarium that’s extremely easy to set up, yet it’s also quite attractive and a very fun display.

It’s currently housing a breeding colony of about 15 adults and all their offspring and it’s far from overcrowded. With that many adults, I find I have at least one pregnant male at any given time, usually more, and births virtually every week. I find it endlessly fascinating to witness the seahorse’s entire cycle of life taking place in microcosm — courting, mating, giving birth, newborns, juveniles and young adults all thriving and growing right alongside the old warhorses.

When my herd of zosterae grows a little more, it will be time to upgrade to a bigger tank. For all practical purposes, I find 25-30 adults can be maintained in a 10-gallon tank set up as described above before water quality becomes problematic (especially if your are raising the young with their patents). Rather than sponge filters, I prefer to use an undergravel filter in conjunction with a very small power filter for a heavily stocked 10-gallon dwarf tank such as that. For such a system, I use an undergravel filter with a single uplift tube and mate the intake tube from the power filter to the UG uplift, so that all the water that goes through the filter first passes through a gravel bed 2-3 inches deep. That simple modification both improves the efficiency of the undergravel filter and prevents the power filter from engulfing dwarf seahorses or their food supply. The small power filter allows filter media such as polyfilter pads and a good grade of activated carbon to be used in the dwarf tank.

Although beginners will be better off keeping a modest herd of dwarves in a small, simple setup like those I’ve described above, there is another type of dwarf tank that works very well for more advanced aquarists. It allows dwarves to be kept in much bigger tanks than is otherwise possible by partitioning or compartmentalizing a large aquarium.

Ordinarily, this is done by using perforated tank dividers to separate a 20-30 gallon (75-114 liters) aquarium into two sections — an equipment area for the filters and such, and a living area for the dwarf seahorses. The perforated barrier allows water to circulate freely between the areas while acting as a baffle that greatly dampens the turbulence generated on the equipment side.

There are some definite advantages to keeping dwarves in a big aquarium this way. For one thing, the larger volume of water gives the aquarium greater stability as far as fluctuations in temperature and pH go, makes it easier to maintain optimum water quality, and just generally gives the hobbyist a greater margin for error. For another, it gives the dwarf keeper better filtration options. For instance, you can’t get a decent protein skimmer for a setup of 5 gallons or less, and power filters create way too much turbulence in small tanks for Pixies. No such problems with the big subdivided tanks. Such setups allow the dwarfs to benefit from the lower volume of water and superior filtration such a system provides, yet the smaller living area makes it easier to maintain a proper feeding density for the pigmy ponies than would be possible in an undivided tank.

For complete details and instructions for setting up the type of dwarf tanks discussed above, as well as other aquarium options for keeping H. zosterae, see Alisa Wagner Abbott’s outstanding new book on dwarf seahorses (The Complete Guide to Dwarf Seahorses in the Aquarium, 2003, 144 pages). It’s the only aquarist’s guidebook ever to be devoted entirely to dwarf seahorses. It includes excellent, up-to-date information, on every aspect of their care and keeping, including breeding and rearing, population dynamics, and maintaining a self-sustaining colony. All in all, a wonderful resource for the dwarf seahorse keeper.

Tankmates for Dwarf Seahorses

Although their small size does indeed limit the suitable tankmates that can be kept with dwarf seahorses, I have found small pipefish do well with H. zosterae. I have a pair of small Gulf Pipefish (Syngnathus sp.) from Florida in my dwarf tank, which add a lot of interest to the aquarium because their behavior is so different from the dwarves (Giwojna, 2005). For example, when they’re just trying to blend into their surroundings, the pipes orient themselves vertically, heads up and tails down, and sidle up alongside a fake gorgonian or a tall clump of sea cactus, imitating one of the branches. It’s not a bad bit of camouflage, and once in a while one of the seahorses perches on a pipefish by mistake and gets taken for a wild ride, like a bareback bronco rider at a rodeo.

But when they’re hunting, the pipes slip into the beds of Caulerpa horizontally, and launch themselves like torpedoes at passing prey (Giwojna, 2005). Unlike the seahorses, which prefer to wait for their prey to come to them, the pipes dart out from hiding and snatch up brine shrimp right and left. It’s amazing how much faster and more agile they are than the pigmy ponies. At feeding time, the pipes go blasting around the tank like little guided missiles. Fortunately, with just two pipefish in the tank, they can’t make a serious dent in the swarms of Artemia.

Like the seahorses, these pipefish are livebearers and give birth to independent babies that are miniature replicas of themselves, except that the newborn pipes are totally transparent (Giwojna, 2005). They look like glass splinters or tiny transparent threads. Although I never made a serious attempt to raise them, a number of them survived for several weeks when left to their own resources in the dwarf tank. They were very good at concealing themselves amid the macroalgae, and especially liked to take refuge amongst the “bristles” of my Merman’s Shaving Brushes. The dwarf seahorses have no interest in them whatsoever, but I strongly suspect the parent pipes are cannibals. All in all, Gulf pipefish are inexpensive and entertaining additions to my dwarf seahorse setup.

For a nice splash of added color and natural beauty, I also like to add an assortment of Feather Dusters (Sabellastatre magnifica and Sabella sp.) amidst my beds of macroalgae. They are the brightly colored flowers blooming among all the greenery of this underwater garden. Feather Dusters are exotic, very showy, entirely harmless, relatively inexpensive, and completely compatible with dwarf seahorses (Giwojna, 2005). They are filter feeders and seem to eat the same newly hatched brine shrimp as dwarf seahorses, but they do best when fed phytoplankton (or commercial food preparations designed for filter-feeding invertebrates) with a baster from time to time.

The Lettuce Nudibranch (Elysia crispata, formerly known as Tridachia crispata, and still usually sold under that name) is another showy, totally innocuous invertebrate that’s a perfect choice for a dwarf seahorse companion. It is green with lavender spots and is covered with extravagant frills and ruffles that look like flower petals on an exotic orchid, but in fact they are the ruffled flaps of tissue (parapodia) that outline each side of the back of this two inch sea slug that lives in the waters of the Caribbean and Florida Keys (Giwojna, 2005). It’s an algae eater that dines on macroalgae such as Caulerpa sertularioides and is one of the few nudibranchs that do well in the aquarium, particularly a dwarf tank with a lush bed of Caulerpa (Giwojna, 2005).

I also have a handful of Volcano shrimp or Hawaiian red feeder shrimp (Halocaridina rubra) in the tank, not as food for the dwarf seahorses but rather as their tankmates. These colorful little saltwater shrimp resemble miniature peppermint shrimp, and usually do well with dwarves because of their size. They are too big to be eaten by the seahorses and too small to be any threat to them, and as an added bonus, they will produce larval shrimp that are perfect treats for the ponies. They are omnivores that do a fair job of scavenging and complement the regular clean-up crew nicely (Giwojna, 2005).

Likewise, live adult Mysis shrimp can also be maintained with dwarf seahorses. They will not harm even the newborn ponies and also produce larval Mysis that the pint-size ponies love to eat. However, the Mysis shrimp will greedily eat newly hatched brine shrimp and you will therefore need to feed the dwarf seahorse tank more heavily if it includes Mysis shrimp. For this reason, it’s best to limit the number of Mysis shrimp to no more than a handful at most.

There are a couple of other types of small, colorful shrimp that can also be kept safely with dwarf seahorses — the beautifully marked Bumblebee Shrimp and Sexy Shrimp.

Sexy shrimp (Thor amboinensis) are colorful and get their common name from their curious undulating dance, which adds to their interest in the aquarium. Their dancing is entertaining to watch and they are peaceful little shrimp get along together in groups or colonies. These boldly marked little shrimp are safe to keep with even newborn dwarf seahorses, but I would fear for their safety in an aquarium with large seahorses such as Mustangs or Sunbursts (Hippocampus erectus). They are very small for shrimp — most specimens I have seen range from about 1/4 to 1/2 inch in length — and that makes them fair game for hungry seahorses. In the ocean, sexy shrimp are often found sheltering in anemones, just as clown fish do, but of course you will be keeping them without a host anemone in your dwarf seahorse tank.

The beautifully striped Bumblebee Shrimp (Gnathophyllum americanum) are another good candidate for a dwarf seahorse tank. The bumble bees are colorful little crustaceans that like to eat the tube feet of echinoderms, and the specialized diet means they have no interest whatsoever in even the tiniest of dwarf seahorses. Aside from their peculiar culinary habits, they are tiny shrimp that never grow larger than an inch in length. Most specimens I have seen are between 1/4″ and 3/4″ in length, which means that large seahorses such as Hippocampus erectus may regard the little bumblebee shrimp as potential prey, although they make good companions for pigmy ponies.

Along with the tiny decorative shrimp mentioned above, assorted snails can serve as the cornerstones of the clean-up crew for dwarf seahorse tanks. The snail assortment may include bumble bee snails, trocha snails, margaritas, Astrea and Cerith snails, etc., but I always make sure to include a few of the smaller species of Nassarius snails.

Nassarius snails are terrific detritivores and amazingly active for snails. They’ll bury themselves until they detect the scent of something edible, and then erupt from the sand and charge out to clean it up.

Most starfish must be avoided when keeping dwarf seahorses because they are a threat to the pigmy ponies and their young, but there are a couple of exceptions to this rule. For example, the Red Bali Starfish (Fromia milliporella) is a small, nonaggressive starfish that feeds primarily on detritus and meiofauna on sandy substrates. The Red Bali Starfish is a tiny species that doesn’t grow to more than 3 inches in diameter (most aquarium specimens are only 1-2 inches in arm span). They thrive in a well-established aquarium with macroalgae and a sand substrate. (However, if you want to add a colorful little Fromia starfish to your dwarf seahorse tank, then you should avoid including any Bumblebee Shrimp, since the bumble bees like to feed on the tube feet of the seahorses. Dwarf seahorse keepers must therefore choose between the colorful Fromia starfish and the attractive Bumblebee Shrimp — they may include one or the other, but not both in their dwarf tanks.)

Also worth considering are the tiny brittle starfish commonly known as Micro-Stars and often marketed as aquarium scavengers or sanitation engineers under that name. They start small and stay small, with a leg span that never exceeds the diameter of a 25-cent piece even when they are fully grown (most of these miniature brittle stars cannot span a 5-cent piece). Their legs are often attractively banded and they are very active and agile scavengers, moving more like miniature octopus that slowpoke sea stars. The micro-stars are fascinating in their own right, but it’s best to limit yourself to one or two of them, since they reproduce very quickly when conditions are to their liking.

Dwarf seahorses are generally considered the easiest of all seahorses to raise. While rearing them is still a challenge, once they’ve gained some valuable experience and straightened out their learning curve, many hobbyists find their dwarf seahorse herds grow steadily. With a short gestation period of around 10 days, and rapidly growing young, H. zosterae will produce three generations in a single year under ideal conditions, which means before long many dwarf seahorse keepers find themselves looking for a larger setup. My own dwarf tank is again fast approaching that point, leaving me with three options: set up a second dwarf tank, move the entire colony into a bigger tank, or find homes for my excess livestock among my fellow hobbyists.

It’s a nice problem to have. And few things are more rewarding to an aquarist than handing out healthy homegrown seahorses to your admiring friends!

Juvenile Rearing Tanks:

Cannibalism is unknown in H. zosterae, and one of the neat things about them is that the fry can be reared in the main tank right alongside their parents since the newborns eat the same foods as the adults. However, for best results, the fry should be reared in a separate nursery tank where the hobbyist can maintain better control over their feeding, growth and development (Bull and Mitchell, 2002, p57). A basic benthic nursery with sponge filters works great for this and can be set up in much the same way as the adult tanks.

More frequent maintenance is required for the nurseries, however. With heavy, continuous feedings in such a small volume of water, regular siphoning is necessary to maintain water quality (Bull and Mitchell, 2002, p57). Fecal pellets and debris should be siphoned from the bare-bottomed nurseries at least twice a day with the deficit made up with new seawater (Bull and Mitchell, 2002, p57). The sponge filters must also be cleaned often as described previously.

The benthic fry thrive on newly hatched brine shrimp (Artemia nauplii) with small, frequent feedings that provide live prey throughout the day. They seek out hitching posts from birth, meaning the fry rarely gulp air, floaters and surface huggers are virtually nonexistent, and they are largely immune from the buoyancy problems that so often plague pelagic seahorse fry.

Experienced aquarists often achieve good success rates (better than 20% survival) in rearing H. zosterae to adults using these simple methods (Bull and Mitchell, 2002, p57).

Diet, Nutrition, and Feeding Techniques:

Adults do well on a staple diet of enriched Artemia nauplii at various stages of development, which have been fortified by feeding the brine shrimp “greenwater” phytoplankton or special enrichment products rich in HUFA (Bull and Mitchell, 2002, p57). Enriched brine shrimp should be offered at least 3 times a day or as often as is convenient (Bull and Mitchell, 2002, p57). This basic diet can be supplemented liberally with copepods, plankton, rotifers, small amphipods and the larval stages of Mysids, ghost shrimp and many other shrimp. If you can possibly provide them, copepods are the ideal food for H. zosterae. Research indicates that in some locations the dwarf seahorse’s diet consists primarily of harpacticoid copepods (Tipton and Bell 1988).

Newborn dwarf seahorses require a constant supply of newly hatched brine shrimp (Artemia nauplii) for the first 2-3 weeks of life until they are big enough to begin taking larger brine shrimp (Bull and Mitchell, 2002, p57).

Some success at getting dwarf seahorses to accept nonliving foods has also been reported by hobbyists. A commercial product consisting of Cyclops copepods in frozen form is sometimes accepted by H. zosterae (Alisa Abbott, pers. comm.) Some hobbyists have also been able to wean dwarf seahorses onto a diet of minced frozen mysids by using juvenile erectus that greedily eat the frozen mysids as role models to teach the dwarves that its edible (Liisa Coit, pers. comm.). The eager feeding of the young erectus appears to stimulate the interest (and appetite) of the H. zosterae and encourages them to try the new food.

If you are interested in attempting to wean dwarf seahorses onto nonliving food such as chopped frozen Mysis, you should wait until they are at least 3 weeks old to begin training them. Keep in mind that they will not be able to take larger pieces of Mysis until they are 3 months old, and be very diligent about cleaning up any leftovers after each training session. Using a role model to teach them the ropes is especially helpful. Be advised, however, that some dwarf seahorses simply never learn to eat frozen foods no matter how much training or coaxing they receive.


Commonly known as the dwarf seahorse, Hippocampus zosterae is the smallest of all the seahorses available to hobbyists. Dwarf seahorses reach a maximum size of about 1.75 inches or 45 mm, half of which is tail. To me, their diminutive dimensions are a source of endless delight; I find them quaint and charming in the extreme (Giwojna, Jun. 2002).
Many specimens are adorned with numerous cirri, giving them a shaggy or weedy appearance that adds to their charm (Giwojna, Jun. 2002). In some individuals, these fancy skin filaments are developed to such an extravagant extent they look downright fuzzy (Giwojna, Jun. 2002).

As I described them in the June 2002 issue of Freshwater And Marine Aquarium: “Of all the seahorses, these exquisite animals were my first love. Thirty years ago, they were the easiest seahorses to feed, accepting newly hatched brine shrimp as their staple diet from the cradle to the grave (Giwojna, Jun. 2002). I could breed them, raise them, and keep them healthy throughout their normal life span at a time when undergravel filters were new and controversial — the cutting edge of aquarium technology (Giwojna, Jun. 2002). My “nursery tank” for the first fry I ever raised to maturity was a mayonnaise jar I rescued from the trash (no such thing as recycling back in those days) (Giwojna, Jun. 2002)!

They remain among my favorite seahorses today, and my preferred setup for keeping them is still a basic 2 to 2.5-gallon aquarium equipped with simple undergravel or foam filters. I find that dwarves tend to get lost (visually that is — the tank appears barren or empty at first glance) in anything much larger than that, and it becomes increasingly difficult to maintain an adequate feeding density of baby brine shrimp for the fry in systems bigger than about 10 gallons unless the tank is partitioned off or subdivided (Giwojna, Jun. 2002).

Dwarves breed best in large groups and are the most sociable of all the seahorses. What makes it extra fun is that these pint-size ponies are as prolific as they are promiscuous. Any time you have an adequate number of H. zosterae together — say several pairs — and conditions are to their liking, mating is a foregone conclusion. Once your dwarf seahorse herd includes 10-12 adults, you can be sure that one or more of the males will be pregnant during the breeding season at all times.”

Heck, anytime you order several pairs of dwarves during the months of May to August, the height of their breeding season, you’re virtually guaranteed that some of the males will be pregnant when they arrive (Abbott 2003). In that case, expect your first dwarf babies to be born in the shipping bags en route or while you’re acclimating your new additions or immediately after you introduce them to the aquarium (Abbott 2003). Or all of the above. Happens all the time!

Far from inhibiting courtship, crowding seems to stimulate breeding in dwarf seahorses, almost as if they reach “critical mass” at a certain population density, triggering a chain reaction of mating attempts. Thus, provided water quality can be maintained, “the more the merrier” appears to be the rule with this species.

For instance, pet dealers must occasionally crowd large numbers of fish together in cramped quarters due to a lack of space, including dwarf seahorses. Robert Straughan was once forced to keep 300 H. zosterae in a 10-gallon tank in such a situation back in the old days, and was pleasantly surprised to find that over 100 of them managed to pair off and breed nonetheless. He reported that at any given moment, dozens of dwarves were actively engaged in courtship, so it was a common sight to witness several couples rising simultaneously to exchange eggs, and that one or more of the gravid males would be delivering young virtually around the clock (Straughan, pers. comm.)!

In terms of their hardiness, fitness for aquarium life, prolific breeding habits, and ease of rearing, dwarf seahorses should be considered the guppies of the sea (Giwojna, Jun. 2002). In fact, this is one seahorse that may enjoy a greater life span in captivity than the wild (Giwojna, Jun. 2002). In nature, winter storms and hurricanes take a heavy toll on their numbers, and very few adult dwarf seahorses survive their first winter; none are known to overwinter twice (Giwojna, Jun. 2002). A detailed field study marked all the individuals of a Cedar Key population and followed them closely for a period of several years (Strawn 1958). The study revealed that the Cedar Key dwarves grew fast, reached sexual maturity early (within 3 months), and died young, with few surviving for more than a year (Strawn 1953; 1958). No 2 year-old specimens were ever observed. (Strawn 1953; 1958) Thus, their natural life span is believed to be about one year in the ocean. In captivity, experienced hobbyists have kept them for 3+ years and not only can they survive to that ripe old age, they are still going strong and may even keep breeding well into their third year. As with other farm-raised seahorses, expect the captive-bred dwarf seahorses to be even hardier than their wild-caught conspecifics.

Nematodes can be a chronic problem with wild-caught dwarves and pigmy seahorses keepers are often plagued by hordes of hydroids and Aiptasia anemones–colonial stinging organisms that kill zosterae babies and injure the adult seahorses, which often subsequently succumb to secondary infections (snout rot; tail rot) (Giwojna, Jun. 2002).
These cnidarians often explode to plague proportions in dwarf tanks because they thrive on the newly hatched brine shrimp that’s fed to the ponies. These persistent pests are the single greatest cause for failure among dwarf seahorse keepers (Abbott 2003).

Nematodes and hydroids (or their hydromedusae stages, which are micro-jellyfish) often enter the aquarium right along with the wild-caught specimens. They typically arrive with WC zosterae or their tankmates, or are introduced shortly thereafter on live plants or live foods (Giwojna, Jun. 2002). Once they gain a foothold in the aquarium they are extremely difficult to eradicate. In fact, once hydroids appear in a dwarf tank, most hobbyists deal with the problem by dismantling the aquarium, sterilizing everything, and starting over from scratch (Alisa Abbott, pers. comm.). Experienced dwarf seahorse keepers often run duplicate setups for that very reason. One tank is the seahorse exhibit; the other is established as a backup tank, held in reserve for the dreaded day when the hydroids appear (Alisa Abbott, pers. comm.). That way, when an infestation inevitably breaks out, the specimens can be given a freshwater dip and transferred safely to the standby tank while the infested tank is taken down, sterilized, and reestablished anew to serve as the backup tank for the next outbreak (Alisa Abbott, pers. comm.).

This is where the domesticated dwarves, farm-raised in Hawaii, have an enormous advantage over wild-caught dwarf seahorses from Florida (Giwojna, Jun. 2002). The CB H. zosterae reach the hobbyist completely free of hydroids and ectoparasites (Giwojna, Jun. 2002). Providing they are then fed with decapsulated Artemia (the decapping process eradicates any and all pathogens or parasites the brine shrimp cysts may have been harboring), chances are great the dwarf seahorse keeper will never have to deal will nematodes or wage war against an invasion of hydroids (Giwojna, Jun. 2002). The trouble-free day of the all-but-indestructible dwarf seahorse has finally dawned (Giwojna, Jun. 2002)!

Cultured H. zosterae are the only captive-bed seahorses that are not pre-trained to eat frozen Mysis (Giwojna, Jun. 2002). The tiny size of these pigmy ponies precludes that possibility. Fortunately, they will thrive on a steady diet of easy-to-provide enriched brine shrimp (Artemia) of all stages from newly-hatched to adult (Giwojna, Jun. 2002). But if you are really interested in dwarf seahorses, I wouldn’t let the fact that they need live food deter you in the least from keeping these amazing little marvels! Hatching brine shrimp for dwarves is a daily chore, but it’s not difficult and quickly becomes routine. Moreover, it is a chore that every seahorse keeper must master sooner or later. Regardless of what species of seahorse you keep, if you want to raise their offspring, you will need to hatch out brine shrimp on a daily basis since that’s the first food most newborns accept. And with dwarf seahorses you are assured that you will always have plenty of fry to raise!

Bottom Line:

Dwarf seahorses are great for beginners and ideal for breeders. Pint-sized and prolific, these pigmy ponies are the perfect pick for anyone primarily interested in rearing or for any seahorse keepers who can’t afford to devote too much money or space to their hobby. Hippocampus zosterae is the best choice for the novice who wants to learn more about keeping and breeding seahorses before moving on to the big boys. More budding seahorse keepers have cut their teeth on dwarves than all the other seahorses put together. H. zosterae is the right pick for newbies who would like to try their hand with seahorses for a modest investment, or for hobbyists with a tight budget, or aquarists looking for captive-bred seahorses that are a snap to breed and a breeze to raise, or anyone captivated by keeping tiny elfin creatures no bigger than your thumbnail. This species gets my highest recommendation.

However, H. zosterae is not a good choice for hobbyists with tanks larger than 10-20 gallons (38-76 liters) for the reasons mentioned above. And this is NOT the seahorse for anyone who minds hatching out brine shrimp on a daily basis.

©Copyright 2009. All rights reserved. Permission to reproduce is granted by the author (Peter Giwojna) for your personal use only and is not transferable without written permission by Ocean Rider and the original author.

Additional Information (to learn more about Hippocampus zosterae, please consult the following references):

Abbott, Alisa Wagner. 2003. The Complete Guide to Dwarf Seahorses in the Aquarium. Neptune City, NJ: TFH Publications.

Heuter, Joanne. 1997. “The Dwarf Seahorse (Hippocampus zosterae).”

Hippocampus zosterae, Dwarf seahorse. 23 Feb. 2004. Fish Base. <;

Masonjones, H. D. and S. M. Lewis. 1996. “Courtship behaviour in the dwarf seahorse, Hippocampus zosterae.” Copeia. 1996(3): 634-640.

Masonjones, H. D. 1997. “Sexual selection in the dwarf seahorse, Hippocampus zosterae (Syngnathidae): An investigation into the mechanisms determining the degree of male vs. female intrasexual competition and intersexual choice.” PhD thesis, Tufts University, U.S.A.

Masonjones, H. D. and S. M. Lewis. 2000. “Differences in potential reproductive rates of male and female seahorses related to courtship roles.” Animal Behaviour, 59: 11-20.

Masonjones, H. D. 2001. “The effect of social context and reproductive status on
the metabolic rates of dwarf seahorses (Hippocampus zosterae).” Comparative
Biochemistry and Physiology A 129, 541-555.

Strawn, Kirk. 1953. “A Study of the Dwarf Seahorse, Hippocampus regulus Ginsburg, at Cedar Key, Florida.” M.Sc. Thesis, University of Florida, 1953.

Strawn, Kirk. 1954. “Keeping and breeding the dwarf seahorse”. Aquarium Journal 25(10), 1954: 215-218, 227, 228.

Strawn, Kirk. 1958. “Life history of the pigmy seahorse Hippocampus zosterae Jordan
and Gilbert, at Cedar Key, Florida.” Copeia, 1958: 16-22.

Tipton, K. and S. S. Bell. 1988. “Forging patterns of two syngnathid fishes: importance of harpacticoid copepods.” Marine Ecology — Progress Series. Vol. 47: 31-43.

Secondly, Richard, here’s an interesting article on dwarf seahorses by Joanne Heuter that has additional tips and information on keeping and caring for these miniature marvels:

The Dwarf Seahorse ( Hippocampus Zosterae ) by Joanne Hueter

For people looking to acquire dwarf seahorses I have decided to try to cover some
of the most asked questions and some interesting things I have learned through
the years, both with the seahorse tanks and my study of the dwarfs in the wild. First
let me tell you a little about myself. I grew up in north eastern United States. When I
was 10 years old I ordered A pair of dwarf seahorses (sometimes called pigmy
seahorses) from the back of a magazine. The male had babies and I think I spent
every waking hour watching the little guys. They were the most fascinating
creatures I had ever seen. Everything went fine with them until that day! It was
about 3 months after I received them. I went into the room where my tank was kept
to see how my seahorses were doing, and there was my 4 year old brother who had
decided the glass on my tank was dirty. He had a bar of soap and was cleaning the
glass from the inside of the tank. Needless to say that was the end of my
seahorses, but I was hooked on the aquarium hobby. To make a long story short I
went from fresh water, to salt water fish, and finally to a reef tank with every new
gadget on the market. About 5 years ago I decided to move to Florida, I sold my live
rock, corals and fish back to the local fish store, and was going to take a rest from
the aquarium. One day while I was walking along a local bay I noticed something
moving along the top of the water. Upon closer inspection I found it to be a dwarf
seahorse, and I remembered the love I had for them as a child. I thought wouldn’t it
be neat to study these guys in their natural environment, to my knowledge there
really has not been much written about them. After studying them in the wild for
about a year or so, I decided to try to recreate their environment in my fish tank.
After all isn’t this every aquarists goal. So out came the tank again. Well enough
about me let us get on to the questions.

What do they Eat
I feed the seahorses live newborn brine shrimp known as nauplii. The eggs are
easily purchased at most good pet stores, instructions for hatching them will be on
the packaging. Basically you just add some eggs to salt water in a jar and an air
stone to make it all bubble. You can use the same salt you use to make the salt
water for your fish tank, high salinity’s 1.025 to 1.035 make for hardier shrimp,
however lower 1.010 and above the shrimp will hatch faster. By the next day you
have millions of live brine. It depends on how many seahorses you have as to how
many brine shrimp you make up at a time. You will use very little eggs. As an
example I have maybe 2 hundred seahorses counting adults, juveniles, and babies
at the time of this writing. I use 1/2 teaspoon of eggs in a one gallon ice tea jar (I
like it because it has a spout) per culture. A culture can last me up to 4 days of
feeding. I add a drop or two of fish vitamins (I use ® Boyd vita chem or ® Selcon) to
the jar about 15 minutes or so before feeding, this will add essential marine fatty
acids and other nutritional additives to the food. When you are ready to feed,
remove the air stone from the jar and wait about 10 minutes for the eggs to float to
the top of the jar. Some of the eggs will be hatched and some may take more time
to hatch, either way you want to try not to put the eggs in your tank, but inevitably
some will get in there. You should make an effort to remove any eggs from your
tank because the eggs are not digestible by the seahorses, and could cause them
problems if eaten. If your jar has a spout just remove a portion of the brine in a cup
and then replace the amount of water removed with some water from your tank, or
premixed salt water. If you don’t have a spout you will have to siphon out some
brine shrimp with a piece of air line tubing. Replace the air stone in the jar and you
are done until the next feeding. They need to be fed at least once a day, but 2 to 3
times would be better. If you would prefer they sell special containers that are
made especially for hatching brine shrimp eggs that may make this task easier. I
have never tried them, but a number of books explain how to make them yourself.
You do not have to worry about over feeding. Seahorses do not have the same type
of stomachs as fish to store food, instead the food somewhat passes through them
and the nutrients and protein are squeezed out of it, and this is why they need to be
feed on a almost constant basis. The only really important part of keeping your
seahorses happy and healthy is proper feeding. In the wild dwarfs eat a variety of
marine plankton. I myself tried to feed them with plankton collected from the area
where they (actually their parents) originate. This was a mistake because along
with the good plankton came bad plankton, that multiplied like crazy and caused
havoc with my tank and seahorses. This was my first problem with trying to
recreate their natural environment. Another option for feeding is marine rotifers,
you can purchase them through mail order in either cysts (eggs) or in a live culture.
I purchased a live culture, food, a special cup for collecting rotifers, and a book on
raising them. The nice part of rotifers is you buy them once and you can have them
forever, the bad part is the food ( some kind of yeast concoction) is a little
expensive and it doesn’t last very long. There is another way to feed the rotifers
and that is with algae, the book goes into detail about this method and its beyond
the scope of this writing. I have found if I keep them in a 5 gallon bucket in my yard
and in the sun they are able to become self sustaining, living off the algae growing
in the bucket. Their life cycle is short and the whole culture dies, but while they are
alive they drop their eggs, and within a couple of weeks the culture is back. In the
winter I let the water dry out and collect the eggs until the next summer. The
seahorses like them, especially the babies (the rotifers are less than half the size
of new born brine shrimp), and I feed them with these only once in a while as a
special treat. They are part of the natural food chain that they would have in the
wild. You will want to be careful not to let any brine shrimp get in with your rotifers
or you could lose your culture, brine shrimp eat rotifers. Also on occasion I will buy
a portion of full grown brine shrimp for them, but only a select few of the seahorses
have learned to eat them. Actually most of them do not consume them whole (I
think they are to big for their mouths), but instead the seahorses kind of suck on
them. Some people have told me that they have slowly adapted their dwarfs to
eating frozen brine shrimp. As of yet I have not tried this.

Filtration for the dwarf seahorses is no different than what you would use for a
typical salt water fish tank. The problems come in the fact that the dwarfs are very
small, the adults are only about an inch long and half of that is tail, therefore they
are prone to be eaten by your filter. I have found a number of ways to get around
this, you can wrap a piece of nylon screen around the intake of the filter or skimmer
box. Another way is to have all your outgoing water go through an under gravel
filter. I have done this on a ten gallon tank with a ®Skilter 250 filter. On the under
gravel filter I use one uplift tube and have placed the intake tube of the skilter inside
the uplift with a piece of flexible tubing to seal it. Another way is to use a separator
plate ( the kind you use to separate fighting fish ), and separate the seahorses from
the filter. I feel this is the best and easiest. While you are feeding your seahorses
you should turn off your filter for a little bit so the food is not going into it, on a wet
dry at least slow down the flow. The seahorses seem to do best in moderate to
slow moving water.

Water Quality
In the backwater bays and estuaries where the dwarfs are found, there is very
poor water quality. The bottom is muck and you sink to your ankles with each step
when you walk in it. If you pick up some of the bottom and smell, it would knock you
over. If you have ever been at the seashore near a bay at low tide, you will know the
smell that I am talking about. I have noted salinity changes from 1.010 to 1.021 in a
1 day period. Throw in constantly changing water temperatures from the tides, and
you have to wonder how any type of fish could live in it. This is a testimony to how
hardy these seahorses are. But the reason for them being there is obvious, since
there is a lot of food for them. When the tide is out and the water is shallow, tide
pools form and the plankton are sometimes concentrated so thick you can barely
see your hand only a few inches below the water. I keep my tanks within the normal
parameter of a salt water fish tank. Ph at 8 to 8.4 nitrate 10 to 15 milligrams per
liter. But I do keep the salinity on the low side between 1.016 to 1.019. They seem
to like the lower salinity better and a lower salinity allows for a higher oxygen
content in the water, but mating does seem to occur more often in around the 1.019
mark. As far as temperature, I keep them at room temperature which can range
from 72 to 86 degrees. In the wild the water temperature can get up to 90 degrees
in the summer, but as winter sets in I have noted that they start heading south at
about 72 to 74 degrees. I do use R/O water in my makeup of salt water for water
changes. I do about a 10 percent water change each week in my tanks, except for
the baby tanks which I do 10 percent each day. I do not believe that it is absolutely
necessary to use R/O water, depending on the quality of your tap water, but I
already had a unit from my reef tank.

Tank Setup
In my tanks I have both plastic plants, live plants, and dried sea fans. The dwarfs
like these because they spend a lot of their time hanging on to them with their tails,
as they would in the wild. I use crushed coral for the bottom. As far as plants in the
wild, I have only found dwarfs in what they call turtle grass, sorry but I do not know
the scientific name. I see no importance to the type of lighting used in the dwarf
tank. The seahorses will be fine as long as that there is enough light that they can
see the food. Some live plants require more lighting to thrive. The actinic lights
work well for this.

Mating in the wild takes place from around May to August, and this is also when
the most mating occurs in the tank. In fact the males are almost always pregnant
during these months. Sometimes the males will blow up their pouches with water
and go around showing the females that he has no eggs. If you have an air stone or
some other type of bubbling device in your tank, and the seahorse is near it when
he blows up his pouch, air can get in and this will put him in trouble. For some
reason they cannot expel this air on their own and they float to the top of the tank.
For this reason I recommend not having an air stone in the tank. If this happens you
have to take the seahorse out of the tank and find the entrance to the pouch, stick it
with a pin while slightly squeezing his sides, if not he could die. If you desire to
have an air stone in your tank be sure to use one that emits large bubbles, because
the small bubbles can be mistaken for food and cause harm to the dwarfs. The
mating begins with a male and female side by side their tails touching, one will
start to quiver from head to tail, then the other will do the same. This can go on
from 1 to 3 days until the female places her eggs into the males pouch. It takes
from 10 to 20 days from this point for the babies to emerge from the father’s pouch.
They come out 1 at a time over a few hour period. The male will be ready to except
more eggs within 3 to 4 days after giving birth. There is no parental care after the
babies are born.

Raising Babies
When the male has it’s babies it can be anywhere from ten to thirty seahorses,
each a miniature of the adults. I start the babies off in a one gallon gold fish bowl
with an under gravel filter and a plastic plant, you can buy a setup like this for
around $10.00. The reason for the smaller tank is two fold. First, you are able to
concentrate the food better, these little guys can eat a lot. Second, the adult
females will sometimes kill the newborns by snapping the back of their necks with
their heads. I don’t know why, maybe competition for food, your guess is as good
as mine. This is the only act of aggression I have ever noted in the seahorses, and
they seem to be smart enough to know not to do this while you are watching them. I
keep the babies from the main tank for at least three weeks. You can either put the
pregnant male in the small tank just before having its babies, or you can remove
them after they are born. I find that a turkey baster works well for this, it is kind of
like a slurp gun used for collecting fish in the wild. Also it is best not to use a net, or
expose the babies to air. The babies do fine on the same newborn brine shrimp as
you would feed the adults. You will find that they are not very active during the first
couple of weeks.

In the Reef Tank
I have never kept dwarfs in a reef tank environment, but I have talked to people
who do. They tell me that dwarfs are well suited for reef tanks that have less active
fish, shrimp, or crabs. The reef should not contain any large sea anemones or the
seahorses could become food for them. In a quiet reef with lots of live rock,
sometimes the dwarfs can become self sustaining living off the small creatures
that inhabit the rocks.

How Long do they Live
I read in a book that dwarf seahorses only live a year or two, but I found this to be
untrue. It is hard to tell each individual seahorse when you have a lot of seahorses,
but let me tell you about Scrappy. He is one of my favorites. When I first started
raising babies over 3 years ago he got caught in my filter. While going through the
impeller his tail was broke and since then he has always had a bent tail. At 3 years
old Scrappy doesn’t look a day over one year. Size does not appear to be a
determining factor for age either, I have both small and larger seahorses that are
the same age. It may be that they are like people, some are short and some are tall.
I do not know any way of telling how old a dwarf seahorse is or how long they live.

How Many Dwarfs in a Tank
I have found that you can keep up to 25 adult dwarfs in a ten gallon tank, and still
maintain an adequate biological balance without a lot of filtration. You may use this
figure to determine the amount of seahorses to keep for your own size tank.

Other Fish with Seahorses
The only other fish I keep with the seahorses are pipefish. These fish are in the
seahorse family and are found in the same waters with the dwarfs, in fact their
appearance is that of a straight seahorse. They eat the same food and get along
with the seahorses very well. Sometimes a dwarf will hold on to a pipefish with his
tail and ride them around the tank. They reproduce much in the same way as the
seahorses, only their pouch with the eggs attached is open all the time when
pregnant. You really should not keep other varieties of fish because seahorses are
not good at competing with them for food, and they will not get enough to eat. I also
keep some turbo grasser snails to keep down the algae growth.

Other Fish in the Wild
As part of my study of the dwarfs, I took an account of other types of fish and
invertebrates that lived in the same area of water with them. I will list them as to the
amount that I found in the water. Some of the species were not there all the time,
and I have also tried to distinguish the predator and the pray.
Grass shrimp (by the thousands) these small shrimp are about 1/2 to 1 inch long.
They are green to translucent in color. Because of their great numbers and small
size its a good possibility that their newborns could be part of the seahorses
natural diet.
Pipefish, there were a good amount of these and they get along well with the
Crabs of many types, Arrow, Spider, and Blue Claw for the most part. I believe that
these could be predators, especially the blue claw, although I have not seen any of
these crabs actually eat a seahorse.
Dwarf seahorses were in small numbers. The most I was able to view in a day of
snorkeling was about 30 specimens, but you have to take into account their ability
to camouflage themselves.
Small Jelly fish, 1 inch size Flounder, 1 inch size Puffer fish, Dragon Wrasses, and
a number of other as yet unidentified small fish in very low numbers.
String rays, actually I have only seen 1 of these in the dwarf patch. I was observing
a group of dwarfs in about a 3 foot circle for quite a while. I moved away from them
to take a look at another area and then I noticed a swirl from the top of the water. It
was about a two foot wide string ray and he was moving around in the same place
the seahorses were. After the stingray left the area I went to observe the
seahorses again and there were none. I do not know whether the seahorses fled
the area or were eaten like popcorn at a Sunday matinee. I would say that they are

Interesting Facts
The dwarfs have two ways to camouflage themselves to avoid capture in the wild.
First they are able to change their color from black to white and a few in-between. I
have seen them in green, gray, brown, yellow, and even on rare occasions orange
and red. They can do this in your tank also, if a dwarf spends a lot of time on one
particular plant it will eventually start to mimic the plants color. Another means of
camouflage are string like appendatures that stick out all over its body and make
them appear to be a piece of sea weed. Within a few weeks in a tank these
disappear, it may be because they no longer have the fear of predators.
Dwarfs unlike some other species of seahorses do not mate and stay with one
seahorse for life. Fact is sometimes a male will gather his eggs from a number of
females at one time. So if someone tells you your getting a mated pair it is not true.
The dwarf seahorse is a little smaller than the size of an adult brine shrimp at birth.
They are born with a larger mouth than even the 12 inch seahorse has at birth. This
is why you can start them off on new born brine shrimp, while the others need
Female dwarfs seem to out number males by almost as much as 10 to 1. I have
noticed this in both my tanks and in the wild.

Just a thought !
People who have lived all their lives in the Tampa Bay area of Florida where I am
living, tell me there was a time when you could see dwarf seahorses by the
thousands. But over the last few years they seem to be disappearing. The fact is in
the last year or so no one I have talked to has seen any. The small area where I
have studied them (a tide pool about 100 feet long and 30 feet wide), is the only
place I have ever seen them and only in very small numbers. I am concerned that
they may be becoming endangered. It could be a problem from pollution. It may just
be in this area, I do not know. I have heard that tons of seahorses are exported
each year to Asian countries from Florida waters, where they are killed and dried to
make medicine and aphrodisiacs. This could be part of the problem. It would really
be a shame to see these wonderful creatures gone forever. If laws are not made to
insure their safety we as aquarists and breeders may be their last hope for

I would just like to say that I do not consider myself an expert on seahorses, and
can only tell you what I have learned from my own experiences thus far. There is
still a lot to learn about dwarfs I am sure. If you find something I have missed in this
writing please let me know. Also if you have something to add from your own
experiences, or perhaps something you have read that may be of interest let me
know also. I would encourage anyone interested in keeping these creatures to try it.

©Copyright 1997 All rights reserved. Permission to
reproduce is granted by the author for your personal use only and is not
transferable without written permission by the original author.

Here is another interesting article on dwarf seahorses, posted by a hobbyist in the Netherlands who works with Hippocampus zosterae, but I thought you might find interesting, Richard. As you will see, he strongly believes that providing the dwarf seahorses with a varied diet produces much better results. He offers his dwarf seahorses a diverse diet (larval Mysis, the copepods Nitokra lacustris and Acartia tonsa, and Moina salina, which are saltwater relatives of freshwater Daphnia) and has tried out many other live foods for them, which may also give you some new ideas:

<Open quote>
In a message dated 1/27/2010 4:07:16 A.M. Central Standard Time, [email protected] writes:
Greetings from Amsterdam,

I originally posted this on <; a Dutch site. I am sorry if I guilty of multiple posting. ***Denotes items not in the original posting.***

Sorry for the English. I just wanted to post about my experience with H. zosterae. I have 34 ***(52 as of 5/1/2010.)*** of them right now. I think my successes with them are due to the fact that I listen & took advice from the people on & ***Many thanks goes to Dan U from Florida, Irene from Sweden, David from Australia & Angi from Germany.***
Listed below are some of the things I learned & resources that I use to buy the items from.

Tank Size: Is a Superfish Aqua Qube 40 with a Sera L 300 sponge filter with a mini 150liter per hour powerhead on it. I use the spraybar attachment that came with the tank. I angled the spraybar towards the surface. I also have a Mini Oxydator for extra oxygen in the tank. Speaking only for myself, I feel a minimum size should be around 20liter. I always ran into problems when I had a smaller size tank with temp fluctuations, ph swings & salinity. Plus if you are new to keeping the H. zosterae, the extra volume will help you out if you overfeed or forget to maintain the salinity. *** The flow doesn’t bother them. They routinely “SURF” in the spraybar wake.***

Temp & Salinity: Temp should range between 21.5 Celsius till 23.5 Celsius and a salinity of 1.019 till 1.022 will suit them nicely.

Decoration & Gravel: I use Indo Black sand from Caribsea, plastic plants, macro algae’s & dry base rock that I cycled using the ammonia method. With live rock, you can introduce hydroids or aiptasia, nuisance algae, crabs, mantis shrimp and so on if you are not careful. I learned this the hard way a few years back and lost 6 of them. If you choose to use live rock, PLEASE quarantine them in a separate tank and see what developed on it. (Just look up posting on people who didnt quarantine their live rocks to see the problems they have with it.)

Tankmates & Cleanup Crew: I have stomatella snails, mini stars, mini brittle stars, very small bristle worms, tisbe, Nitokra lacustris, peppermint shrimp & mysis in with them. You could use nassarius snail, mini hermit crabs & peppermint shrimp at your own risk. Some people like them & other people do not. Just keep an eye out for them. ***NOTE*** Peppermint shrimp are evil. They ate all of the mysis.

Diet: It is very important that you vary their diet. Since I changed their diet to this method, I am having more active H. zosterae. I feed them baby brine shrimp/artemia up to 5 day old enriched brine/artemia, tisbe, nitokra lacustris, moina salina, tonsa & mysis. Here is how I culture them.

Brine shrimp/Artemia: I use a Hatcher for the brine/artemia. Once they hatch, I place them in two 1.5liter bottles with a mixture of nanno & iso. After they are 24 hours old, I enrich them with one of the following product, AlgaMac-3050, NatuRose, Spirulina Powder & HUFA. I do this until they are 5days old, after that they are fed to the mysis. ***(Also read the thread: Passing out cigars for advice from Dan U.)*** I started hatching them this way.***

I use the vases because I ran out of room. You can use whatever containers suit you.

Tisbe: Are cultured in a 6 liter vase with greenwater with an airflow rate of two to three bubbles per second. I feed them1 -2 pieces of mysis just before I turn off the lights. If it is still there in the morning that is ok. When you turn on the lights in the morning & it is gone, add one extra piece to mysis to the nightly feeding. Increase accordingly. I harvest them weekly & put them in with the H. zosterae or to feed them to my H. reidi fry’s.

Nitokra lacustris: Are cultured in a 6 liter vase with greenwater with an airflow rate of two to three bubbles per second. I feed them 1 -2 pieces of flake just before I turn off the lights. If it is still there in the morning that is ok. When you turn on the lights in the morning & it is gone, add one extra piece flake to the nightly feeding. Increase accordingly. I harvest them weekly & put them in with the H. zosterae or to feed them to my H. reidi fry’s.

Tonsa: Are cultured in a 6 liter vase with a mixture of iso & nanno greenwater with an airflow rate of two to three bubbles per second. They need a light on them to keep the water green & for them to eat. When the water clears, add more greenwater. Also when you vacuum the bottom during a WC, put that gunk into a 1.5liter bottle. Within a week, the eggs should hatch out.

Moina salina: Are cultured in a 6 liter vase with a mixture of iso & nanno greenwater with an airflow rate of two to three bubbles per second. They need a light on them to keep the water green & for them to eat. When the water clears, add more greenwater. Also when you vacuum the bottom during a WC, put that gunk into a 1.5liter bottle. Within a week, the eggs should hatch out.

With the tonsa & moina, I strain then thru a fine mesh and feed them out to the H. zosterae.

The tisbe & nitokra can be placed next to them to share the light. They normally come out in the dark. Provide them with some LARGE PORES sponges to live in.

Mysis: The live mysis themselves serves as part of the cleanup crew and in return the mysis nauplii are a great food source for the H. zosterae. Dan Underwood from started adding the mysis in with his breeding stock. He is reporting that the H. zosterae actively hunt down the new born mysis & that the males are giving birth to bigger litters. (See this tread Live Mysids With Dwarfs)

PLEASE NOTE: I buy the live mysis for my 6 H. reidi & 1 H. comes. I keep the mysis in the 40liter bare bottom tank with a sponge filter with a mini power & an airline set at 10 to 15 bubbles a second. I rinse the sponge filter weekly (It is SO FULL of gunk.) when I do the 25% water change.

To get the mysis ready for the H. zosterae tank, this is what I do: When I buy them from the store here, the salinity is around 1.004 to 1.012. I slowly adjust it up to 1.020/1.022 level of saltwater. I do this in a separate container. It takes me three to four days to adjust them. I add nanno & iso at a rate of 10% to their weekly 25% water changes. I rinse the sponge filter weekly. (It is SO FULL of gunk.)

I feed both tanks any of the following items. Flake food, freeze dry cyclopeeze, Reef-bugs, bbs, pellet food, Formula One & Two frozen/flake, Vita-chem soaked freeze dry food, algamac-3050, naturose, spirulina powder and of course mysis. If I have agar on hand, I mixed all the dry ingredients in a mortar & pestle along with garlic & vita-chem to make my own food.

Once the Mysis are in with the H. zosterae, they will eat the leftover & dead brine/artemia. They do a very good job of keeping the tank nice & clean. I have between 50 to 75 mysis in the tank with them at the moement. ***I top off every week or so. Some adults die or got eaten.***

Plankton Culture: I am culturing Isochrysis &Nannochloropsis for now. The Iso is cultured in a ten liter plankton reactor and the nanno are cultured in 1.5 liters bottles. I use a 50/50 mix for the brine/artemia. This is the base in which I add the enrichment products to.

Peppermint Shrimp: They serve the same purpose as the mysis. Be aware that they could attack the H. zosterae if they are NOT THE TRUE PEPPERMINT SHRIMP. It is up to you to make sure that you are getting the true peppermint. *** I no longer keep the shrimp in with the H. zosterae. They ate all of the mysis. I now have them in a 20liter tank & harvest the nauplii for the H. zosterae.***

Pest: Hydroids or aiptasia are deadly to the H. zosterae. Please consult this forum or the other two forums on how to deal with them

Problems with my set-up: Since I do not have a protein skimmer on the tank, I develop an oily slick on the surface on the water. I remove this film with cling wrap/vershoudfolie. I turn off the powerhead and lay a piece of the wrap on the surface. The oily slick is attracted to the cling wrap. Repeat until it clears. Another problem I have is that some of the mysis jump out of the tank or they land on the underside of the glass top. This is due to the gap surrounding the tank. ***Will add a Sander air driven skimmer at the end of January.***

Water changes & daily chores: I do a 25% water change weekly on the tank. The replacement water is around 20% greenwater & 80% saltwater. I spend around 45mintue to an hour a day just for the H. zosterae. I find it very relaxing taking care of them. The greenwater is to feed the tonsa & moina I always try to keep in the tank. I keep only the front panel clear & let the algae grow on the other panels. This is eaten by the stomatella snails, mysis & copepods.

Prices & Sources: I have been quoted €125.00 to €155.00 each in The Netherlands. I bought some from Helen @ for 65.00 pounds each plus 40.00 pounds shipping. I ordered 10 of them from her. Due to a freak accident, I lost two of them. Helen gave me credit right away on them. The second group I bought the stock from a private person. I pay €75.00 each for them. Helen just received 100 with the C.I.T.E.S. Permit. Chances are if you buy them from a store here, they came from Helen. The easiest way to find out is to ask to see the C.I.T.E.S. Permit. ***The private person is Angi from Germany. I met her on M.O.F.I.B.***

Also when the weather warms up, I like to share my pod cultures with people. I do it on the PAY IT FORWARD SYSTEM. You only have to pay for the box & shipping. The pod starter cultures you get for free. When you find that you have more than you need, you past it on to the next person for free. You are allowed to ask for the cost of the box & shipping, but you are not allowed to profit from it. It is VERY BAD KARMA to ask for money on something you got for free.

Lastly, NONE of my H. zosterae is for sale at the moement. I am willing to trade with other H. zosterae owner to increase my bloodline. Right now I have USA/UK, German & Dutch bloodlines. I am working on getting some Swedish bloodline. ***I wanted 50 before I sell. Since I reached that goal, I want 75 now before I sell***

In conclusion, I just wanted to share my experiences with these wonderful creatures. Since they are so rare & hard to come by in Europe, we need to help each other out.



Reading Resources: File # SR487.pdf


Copepod Culture

Sources of H. zosterae within the EU:




The Plankton Culture Manual. A MUST HAVE BOOK.

Amendments to the post 6/1/2010:

As of 31/12/2009 I have: (40+) H. zosterae 24 adults, 9 @ 4 weeks, 6 @ 2 weeks & 4 @ 4 days.

As of 5/1/2010 add 14 @ one day old.

Two of the adults are from Helen’s last year. (Sold the 6 other) The other adults are from Germany. I feel that varying their diet & taking better care of the brine/artemia helped with the birth rate.

When I find more space, I will move the tonsa & monia cultures to 20 liter tanks. I cannot produce enough of them to feed the H. zosterae. Right now I produce enough for a weekly feeding. I would like to increase it to three or four times a week. I will also try an outdoor culture like Angi told me about come spring.

Since three weeks ago, I have been unable to purchase live mysis. I have enough to replace them in the H.zosterae tank, butnot enough for the other seahorses. Once the ice is gone, I should be able to get them again.

One thing I am learning from all of the sites, it that we all do some things the same and some things different base on the country.
<Close quote>

Okay, Richard, that’s the latest thinking on keeping Hippocampus zosterae from Amsterdam. Hopefully, it will give you some good ideas to pursue in your quest to provide additional live foods for the dwarf seahorses.

Finally, here’s an old article on dwarf seahorses by Kirk Strawn that you might find interesting if you have not already seen it, Richard:

“Keeping and Breeding the Dwarf Seahorse”
by Kirk Strawn (University of Texas)

“Hippocampus zostrae (Jordan and Gilbert) is one of the best marine fish for the home aquarium. This little fish (adult size is from 3/4 to 1-3/4 inches) will prosper and breed in a gallon or two of water and it does not eat its alive born young. The eggs are deposited in the pouch of the male following a beautiful courtship in which both fish take an active part. All sizes of dwarf seahorses are easily fed on newly hatched brine shrimp, the only saltwater live food available to most aquarists. Few animals can match its ability to change color. By furnishing the proper background and light, it becomes gray, a clear light yellow, white, black, and numerous shades of both green and brown. These changes are not sudden but take place over the course of several hours.”

“…They live in shallow water around the low tide level. (A larger seahorse, Hippocampus hudsonius, is present in the same areas, but, except for a few strays, it lives in deeper water.) Being weak swimmers, dwarf seahorses avoid being swept about with the tidal currents by wrapping their prehensile tails around the seed plants and algae among which they live. These seed plants, Cymodocca manatorum, Halodule wrightii, Halophila engel-manni, and Thalassia testudinium, characterized their habitat. These phanetograms are very similar in growth form to Sagittaria and Vallisneria and would enhance any aquarist’s tanks. Beautiful little Halophila with its rosette of leaves has no equivalent in the freshwater aquarium. When some aquarist discovers how to propagate these plants in the home aquarium, the beauty of marine tanks will be greatly enhanced. Some of the algae prosper in the aquarium and provides excellent purchase for the seahorses. If no perches are provided, seahorses greatly annoy each other by wrapping their tails around one another. Polyps are frequently present on the algae. Both these polyps and the little jellyfish they produce compete with the seahorses for brine shrimp. Unless one likes jellyfish they should be eliminated.” (I.e., hydroids and hydromedusae)

“The dwarf seahorse feeds only on live, moving food. In nature it feeds on small crustaceans, i.e. copepods and amphipods that cling to plants. Swift-moving, open water copepods are too fast for it to capture. In the aquarium it readily eats newly hatched brine shrimp. Only gentle aeration should be used because strong aeration whirls the brine shrimp around too fast for the seahorses to capture them. Newly hatched brine shrimp live for at least two or three days with the seahorses. Thus feeding them every other day will keep live food constantly before them. Small brine shrimp should be kept with the seahorses at all times. Poorly fed adults die in two or three weeks. Starvation for a day seriously runts young dwarfs and several days without food results in death (for the babies). Brine shrimp eggs should not be placed in a seahorse tank because they tend to foul the water. Herald and Rakowicz (1951) found that brine shrimp eggs killed small Hippocampus hudsonius by clogging the intestine, but this is not been observed in the dwarfs. Dead brine shrimp and seahorse droppings need to be siphoned off the bottom and the strained water returned to the aquarium or replaced with new seawater.

The dwarf seahorse does not feed in dim light, so good illumination is a necessity. At Cedar Key, on the northern Gulf coast of peninsular Florida, it does not breed when the period from sunrise to sunset is less than 11 hours and it breeds best when the days are longer than 12 hours. This indicates the dwarf seahorse should be furnished with at least 12 hours of light a day. My seahorses received constant light. Most writings on marine aquaria recommend dim light to avoid green water. In my bowls, glass wool and bone carbon filtration quickly cleared green seawater. Filtration also removed the brine shrimp and baby seahorses and consequently should be used only occasionally, unless a means of keeping the brine shrimp and baby seahorses from entering the filter is provided. A scum of blue-green algae sometimes develops. It can be removed from the side of the tank with an aquarium scraper and from the algae used as a perch by rinsing it under a faucet.

A knowledge of the salinities found in the native habitat of marine aquarium fishes is a great aid to their maintenance in the aquarium. Information concerning the salinities in many coastal areas can be found in the “Density of Sea Water at Coast and Geodetic Survey Tide Stations Atlantic and Gulf Coasts,” which can be obtained from the Department of Commerce, US Coast and Geodetic Survey, Washington, DC. Salinity represents the approximate weight in grams of total dissolved solids per 1000 g of water. These symbols 0/00 is used to represent parts per thousand just add 0/0 is used to represent parts per hundred. In coastal regions such as Tampa Bay and Cedar Key, Florida, where river discharge dilutes the seawater, dwarf seahorses prospered in a wide range of salinities as shown in Figure 1. If they lived at Miami or Key West, they would be accompanied to rather constant salinities in the mid-thirties. They live in even higher salinities and the lagoons along the dry coast of northern Mexico and lower Texas where evaporation frequently raises the salinity above that of the Gulf Stream at Key West. High salinity seawater is a much better buy than low salinity seawater. Over 1.7 gallons of (15?) 0/00 seawater for Tampa Bay and Cedar Key can be made from 1 gallon of 35 0/00 seawater by adding freshwater, or over 1.7 gallons of (15?) 0/00 seawater would have to be evaporated down to 1 gallon to furnish water in the usual salinity range of Key West dwarf seahorses. Fresh or preferably distilled water should be added to the seahorse tank to replace evaporated water. I change water every two weeks to once a month. Some dwarf seahorse keepers use their water much longer. Breder and Howley (1931) found marine water in which fish are kept tends to become acid and that the fish no longer prosper when the pH drops. The seahorse water undoubtedly could be used much longer than two to four weeks if their method of adding sodium bicarbonate to maintain the pH of 8.2 were followed.

Dwarf seahorses can withstand a wide range of temperatures. I have seen them existing in nature in water from 43°F to 98°F. They were not very active at 98°F, and the one observed at 43°F laid on its side and barely wriggled. Ice forms during extremely cold low tide periods in their habitat on the northern parts of the Gulf coast, so they must survive, at least temporarily, at temperatures lower than 43°F. They should do well in the aquarium at temperatures ranging from 65°F to 90°F. Seawater may suddenly become foul at high temperatures so the seahorse aquarium should be kept especially clean if the temperature is in the higher 80s.

The aquarist is not giving his seahorses natural conditions when he keeps them in a still-water aquarium. In nature tidal currents, wind, and waves are usually mixing the well aerated surface film water with the deeper water. In the aquarium, the bubbles from an airstone can be used to give motion to the water and increase the air-water surface area. Unfed dwarf seahorses will live in clean unaerated water until they starve to death. Once food is added some type of aeration helps prevent fouling of the water and subsequent death of the seahorses.

Harbor Island H. Zosterae in the Home Aquarium

In February, 1951, I collected several pairs of dwarf seahorses at Harbor Island near Port Aransas, Texas. Each pair was placed in a two-gallon glass drum containing about a gallon and a half of seawater. One male survive until November. The others died in September while in the care of a friend. I had not expected them to live this long because wild Cedar Key dwarf seahorses apparently do not reach this age. At Cedar Key only adult dwarfs are present in late January. These over-wintering fish start breeding in late February. The size difference between the old fish and their young is greatly diminished by mid-summer, but it remains sufficient for one to distinguish between the two groups. The old fish become fewer in number as the summer progresses and entirely disappear by late August.

None of the fish collected in January were in breeding condition. After three weeks in the Aquarium Room at the University of Texas, several pairs were courting. Although males frequently looked gravid, only two small broods were born. The fault evidently lay with the females because a male put with a freshly caught, ripe female had a full brood. Breeding fish caught at Harbor Island in early June continued to breed until they were moved to a poorly lighted room well the Aquarium Room was being painted.

They are prolific little fish. The eggs take about 10 days to develop in the pouch of the male, and the male is ready to breed a day or two after delivery. One male had a brood on the 15th of June and another brood just after midnight on the 27th (of June). The young may number as high as 55 though 25 is a more usual brood size.

”Unguarded airstones disrupted many courtships. A courting male pumps up his brood pouch with water until it appears ready to burst. When this action occurs in the stream of bubbles above an air stone, a bubble is likely to be sucked into the pouch producing a disastrous effect on courtship. The male swims over to meet the female. When the air bubble in the brood pouch shifts, he loses balance and floats tail first to the surface. With great effort he swims down to a perch and wraps his tail around it. Firmly anchored, he resumes an upright position. The female comes over and wraps her tail around his. When she moves away, he follows, loses his balance, and shoots to the surface. Finally the pair give up trying to breed. These bubbles remain in the pouch unless removed. In nature death would surely result either by the male’s being washed ashore or from its being exposed to predators. In the aquarium a floating male can live indefinitely.

Herald and Rakowicz (1951) found bubbles to occur in the large seahorses, Hippocampus hudsonius punctatus, as the result of gas given off by decaying young remaining in the pouch after delivery. They recommended removing the bubble by inserting a needle into the opening of the pouch after delivery. This is a more difficult operation on the little dwarfs. It is more easily accomplished either during courtship or following the delivery of young — at which times the opening to the pouch is dilated. Inserting a needle through the entrance of the pouch does not ruin a male for future breeding. A male kept away from females from February until June had bubbles removed on three occasions by puncturing the side of the pouch with a needle and squeezing out the bubble. (Males go through the motions of courtship and may pick up bubbles even if no females are present.) On June seventh he was placed with a ripe, freshly caught female. On the seventeenth I cut a slit in the side of the pouch and removed a bubble and two partly formed babies. By the twentieth [3 days later] the slit was healed over, and he had another air bubble. On the 23rd I partially removed this bubble by forcing a needle through the entrance of the pouch. On the 25th [2 days later] yolk came out when the needle was inserted. On July 5th he gave birth to a large brood after which a bubble was squeezed out of the dilated opening of the pouch without the aid of a needle. The next day he sucked in another bubble while courting. Although removing bubbles does not permanently damage the fish, it is much easier to put a fence, such as a cylinder of plastic screen, around the air stone and its rising stream of bubbles.

Most of the broods were preserved soon after birth for use in an investigation of the range of variation of taxonomic characters in a single brood. One brood was raised in a two-gallon bowl for a month and a half and then transferred to a 10 gallon tank. At two months 42 were still alive.

The many qualities that make dwarf seahorses the pride and joy of their owners justify any aquarist’s expanding his fish-keeping techniques to include this ideal little marine fish. Even the inland aquarist who has difficulty getting seawater in quantity should not find it is difficult to keep and breed as many of the popular freshwater fishes.

The End

Last but not least, Richard, here are some suggestions from other hobbyists regarding the setups they prefer for dwarf seahorses. It might give you a better idea of what type of setup will work the best for you for your dwarf seahorses.

Susan’s Tips for Raising Dwarf Seahorses (Hippocampus zosterae)

Hi Ricky,

We raise the dwarfs, as we call them. They are hardier than the big guys in my opinion, the only problem is keeping up with raising the baby brine.

We have had them in a 10 gallon for the past year and are ready to move them into a 15 real soon, they had a lot of babies this past year.

We use an Aqua Clear filter, the #20, on low. I put a sponge filter around the intake, and shut the filter off and clean the sponge everyday. When we move them into the 15, we’ll use the same filter, only set on high. Sometimes they like to play in the current and sometimes they just go to the other side of the tank where we have a couple seahorse tree’s. You’ve probably seen them at the lfs. We have one natural tree as well.

Also, on that side of the tank, I have a solid air tube that I took from one of those sponge filters. Just took the sponge off and use the air to keep anything from accumulating at the top.

When it is bright out, I keep the light off of the tank because otherwise the bbs go to the top and the dwarfs being lazy, like the food to come to them.

Keep your eyes out for hydroids as they love the same environment as the dwarfs. Panacur works great, and we haven’t had a problem since.

Happy to help with any other questions.

PS. I forgot to mention that I enrich the bbs with teeny amount of Vibrance. Susan

rlbailey2005 wrote:
Hey Everyone! I just got back last week from Florida and I went to the
Tampa Aquarium. They had a marvellous display of seahorses. I believe
their were six different species in all. I also got to see my first
tank of Pixies in person and are they cute. I have read up on them
somewhat, mainly that they eat only live brine shrimp and have small
tank requirements and very very low water circulation from a pump. I
have thought about setting up a 10 gallon tank for some and was
wondering what kind of filtration I should use and how many I could
keep in a 10 gallon tank. I think its cool that the babies can grow up
right with thier parents. I also thought about getting a 10 gallon
eclipse system for them but I have not decided which would be best. So
that’s where the group comes in. I would like to get everyones opinion
on this subject and would especially like to hear from those that have
pixies. Thanks

“D’s” Tips for Raising Dwarf Seahorses


Have you convinced Tonya to join you in this adventure ;>).

By no stretch of anyone’s imagination am I an expert but I created a
small tank set up that was (and still is for my mother) successful for
a small shield of dwarves that may be of interest. It is the only set
up where I was able to raise to adult any of the dwarf babies.

I found a small 1.5 gallon (I think they are actually listed as 2
gallon but they do not hold that much) hexagonal acrylic tank. They
are under $30 at Petsmart and made of VERY scratch resistent acrylic.
They come with a light fixture and single tube undergravel filter

I added a Red Sea cascading filter (made for Nanos and is very
impressive for this sized tank with an adjustable flow control and a
slot for filtration that can easily use a piece of any media cut to
fit or small charcoal bag).

I run the filter intake into the under gravel and block off the gap
with a sponge (the horses WILL get into the tube if you do not block
the gap and you must close it off when cleaning the intake tube). The
flat acrylic cover needs modification to fit the cascade filter (it
could be left off but it protects the light from the saltwater) so I
cut it to the size of the light cover(two straight cuts – chop saw
does it quickly), leaving gaps between the front and back of the light
fixture. The front gap is perfect for feeding with the little cups
from the brine shrimp hatchers I use from Brine Shrimp Direct (see
prior posts or email me if you would like details). I also cut a
round hole in the light fixture top (a little tricky but I used a hole
saw bit and drill) to allow more heat to escape since I use a 50/50
actinic instead of the bulb that comes with it. The light fixture
uses a standard screw bulb so there is plenty of room for
experimentation. I also had to make a small nick on the back of the
light hood to accomodate the filter down tube but it was a minimal cut
and the unit looks quite presentable.

This was my most successful set up for the dwarves and the only one
where I successfully raised any babies. I did use a piece of live
rock (pretreated with worm killer) for the setup given to my mother at
Christmas and there have never been hydroids. It needs much more
frequent water changes than a larger tank – about 1 cup a day but the
water change takes less time than feeding. Algae growth is also a
problem but that is more likely my lighting than anything directly
related to the tank. Not using live rock should also help with algae

I no longer raise the dwarves for myself but help maintain the set up
for my mother (I provide water, shrimp eggs and occassional tank
cleaning). However, I still use two of these little tanks for varying
adventures. Currently, I have a small slipper lobster and serpent
star in one and keep an “undesireables” tank with the other (aptasia
can be interesting – OUTSIDE of your reef/horse tanks ;>).


Ken’s Office Dwarf Seahorse Setup (2.5 gallons)

I set up a 2.5 gal tank at my office, and have had a pair of dwarf
seahorses in since June 20. They mated in the first week, and I
already have 8 healthy looking babies. Nitrites were a little high
this week, so I did two 25% water changes this evening and need to do
one more. The test says it is still in the low end of the “stress”

I have been decapsulating small batches of brine shrimp eggs daily
and setting them aside to hatch in large pill bottles. I use a
baster to siphon out the hatchlings. This has worked okay, but I
think I will set up the 2 liter bottle hatchery thing for better

On the weekends when I am away, I will allow eggs to hatch directly
in the tank. When I come back in after the weekend, I will switch J
tubes on the palm filter to allow full force of the filter to suck
the trash out of the tank, watching carefully to make sure no horses
get sucked through the strainer end, then replace the retroffited J
tube and sponge back into the filter, replace the poly filter, do a
water change and add freshly hatched brinies.

This is a pretty easy method, and only takes about an hour a week to
maintain, (aside from doodling with brinies a couple times a day).

I hope I can raise those babies up to adults. 🙂

Ken. (continued below)

I like to use the Azoo palm filter with a Poly filter in it instead of
the using the little fitler pads that come with it. The flow of the
filter is too powerful for my tastes, so I put a baffel in the J tube
to slow the water down. A sponge filter on the intake keeps the baby
brine from being sucked in.

See my design here:


I am happy with this design and thought others might like to see it.

These were taken with my cell phone camera. Not the greatest, but good
enough to share.


Ken’s Dwarf Seahorse Desk Top Setup Update (Ultimate Seahorse)

I have been keeping 2 adult h.zost in a 2.5 gallon tank for 2 months
now. They are happy little horses. I have removed the baffel from the
filter arrangment and I am letting the Azoo palm filter run with it’s
own flow regulator on the low setting. Still have the azoo bio sponge
over the intake. I change about .5 gallon of water per week and
change the poly filter in the Palm filter once a week. I also squish
out the sponge once a week in clean salt water to remove the junk.

I am finding that this little tank is pretty manageable, but I test it
every day to make sure.

Feeding baby brine and some 3 day old brinies fortified with algea
paste once a week.

All is well.


Hopefully, you will now have a better idea of the different options for setting up a seahorse tank for Hippocampus zosterae, Richard. Relatively small tanks are generally best and very simple filtration systems can be quite effective.

Happy Trails!
Pete Giwojna, Ocean Rider Tech Support

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