Pete Giwojna

Dear Glen:

Here are some quick tips explaining how to set up and maintain a simple nursery tank for your seahorse fry, sir:

Basic Nursery Tank

The simplest nursery tank setup is a bare bottom 5 to 10-gallon glass tank equipped with suitable hitching posts, an air-operated sponge or foam filter, and nothing else (Giwojna, Jan. 1997). Add a cartridge of activated carbon to the airlift tube of the sponge filter(s) to provide a little chemical filtration.

Keep the sponge filters in such nurseries elevated or prop them up off of the bottom. Otherwise they can become death traps for unwary benthic fry, which can become wedged beneath them and trapped. Adjust the airflow through the sponge so it produces a stream of small, steady bubbles. You want to create a slow, gentle flow through the foam filter without generating overly fine or excessively large bubbles (Giwojna, Jan. 1997). Seahorse fry may accidentally ingest fine bubbles, mistaking them for food, while large bubbles can buffet the newborns with harmful results (Giwojna, Jan. 1997). Too much airflow through the sponge filters will leave them prone to “eating” the fry’s food (newly hatched Artemia, copepods, rotifers, etc.).

At the same time, however, you want the air stream to break up surface tension and provide adequate surface agitation. This is important not only for efficient oxygenation and gas exchange at the air/water interface, but also to allow the fry easy access to the surface. A newborn’s first instinct is to head to the surface to fill its swim bladder. (Physosymotous fishes have a connection between their gas bladder and the gut in the form of an open tube called the pneumatic duct, and are thus able to fill the swim bladder by gulping air at the surface. Like many teleost fishes, seahorses lose this connection very early in life, so that their swim bladders are completed closed as adults.) In many species, gulping air is the way in which gas is first introduced into the larvae’s bladder, and if denied an opportunity to do so, their development is hampered due to uninflated swim bladders (Silveira, 2000).

This is the case with seahorse fry. If denied access to the surface to inflate their swim bladders, the fry behave normally while they are small and their weight is still negligible. But over the weeks, as they grow and put on weight, their underdeveloped swim bladders and inability to achieve neutral buoyancy increasingly handicap them. Once they gain a little weight, they sink like rocks. Unable to swim, they are reduced to slithering along the bottom on their bellies and are commonly referred to as sliders. This deficiency does not become apparent until the fry are several weeks old. Needless to say, this hinders their swimming ability and severely limits their feeding opportunities, delaying their growth and development, and rendering entire broods useless. In several cases, the problem was traced back to an oily film on the surface of the nursery tank, which prevented the newborns from filling their swim bladders with air (Silveira, 2000). A protein skimmer will prevent this by removing filmy surface layers and surfactants in general.

The same sort of sponge filters that work well for dwarf seahorse tanks are also ideal for nursery tanks. Be sure to avoid sponge filters with weighted bottoms or other metal components since they will rust when exposed to saltwater. Sooner or later this will cause problems in a marine aquarium (sooner in the small nursery tanks). 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.

The sponge filters I find that work well are the Oxygen Plus Bio-Filters (models 2, 3, 4, or 5) or the Tetra Brilliant foam filters. They have no metal components, making them completely safe for use in saltwater, and just one of these foam filters will do the job on a tank of 5 gallons or less. They do not have a weighted bottom but are equipped with suction cups instead.

Foam Aquarium Filters: Oxygen Plus Bio-Filter 2

http://www.drsfostersmith.com/product/prod_Display.cfm?siteid=6&pCatId=3936

Avoid the Oxygen Plus Bio-filter 6, 11, and the Multi sponge, which all have a weighted bottom (metal), that rusts when exposed to saltwater. If you want more filtration, you’re better off going with two of the smaller suction cup sponge filters rather than any of the models with weighted bottoms. For instance, for a 10-gallon tank, I’d suggest using two well-established foam filters, one at either end of the tank for the biofiltration, just as you are planning, Glen.

All you need to operate sponge or foam filters is an inexpensive, diaphragm-operated air pump (whatever is available at a reasonable price from your LFS will do just fine), a length of airline tubing to connect the air pump to the foam filter(s), and a set of air valves (gang valves) to regulate the air flow to the filters. That’s all — nothing to it! The inexpensive Apollo 5 air pumps work great for sponge filters, but whatever air pump you have on hand should certainly do the job.

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. (I use the saltwater I siphoned out of my aquarium when performing a water change for this, and clean my sponge filters whenever I change water.) 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.

Setting Up & Maintaining the Nursery.

The nursery tank(s) should be filled with water taken from the main tank that houses their parents, so the delicate newborns can be transferred directly to the nursery without adjusting to any stressful changes in pH, temperature or salinity (Giwojna, Jan. 1997). Cured ”seahorse trees” make good hitching posts, as do artificial aquarium decorations such as small seafans and soft plastic plants with fine, branching leaves (Giwojna, Jan. 1997). Strips, sections, and cylinders of plastic window screen or the plastic mesh sold in craft stores for needlepoint projects also work well. Short lengths of polypropylene rope (the kind sold at hardware stores and marine outlets for boating purposes) are another good option for hitching posts in the nursery. They come in many different colors, can be cut to any desired length, and are buoyant so if one end is anchored and the other end is unraveled, they will wave gently in the current like natural plants. (Avoid nylon rope, however — it bleeds in saltwater and will leech color and who knows what else into your tank!) If necessary, the holdfasts can be secured to the bare glass with silicone aquarium cement or suction cups designed for use in marine aquaria, or secured to a piece of coral rubble to anchor them in place.

If you can obtain the fine-bladed or feathery varieties, live Caulerpa will help maintain good water quality by removing excess nitrates, as well as providing natural hitching posts that help benthic seahorse fry feel right at home (Giwojna, Jan. 1997). These marine plants grow from woody holdfasts and don’t need to be anchored in a sand or gravel substrate, so they’ll do fine in a bare-bottomed nursery (Giwojna, Jan. 1997). However, live Caulerpa is more difficult to keep clean and sanitary, and for this reason, many breeders prefer artificial hitching posts for their nurseries such as those described above (Mai 2004b).

In addition, hydroids and miniature jellyfish (the free-swimming hydromedusae stage of the hydroids) are often present on live marine plants, and they can easily be accidentally introduced to the aquarium along with the Caulerpa. Ordinarily, this is not a problem for the greater seahorses, but hydrozoans can wreak havoc when they become established in a nursery tank. Not only will they compete with the fry for food, their stings can be lethal to the babies or leave them susceptible to secondary infections (Vincent, 1995c), and hydroids are sometimes responsible for mass mortalities in nurseries.

A brief quarantine period for Caulerpa and other marine plants, during which they can be treated with fenbendazole granules for several days, is therefore strongly advised. Fenbendazole is an inexpensive deworming agent used for hoses and other large animals, and treating the quarantine tank with 1/8 teaspoon per 10 gallons is guaranteed to eradicate hydroids before they can gain a foothold in your nursery tank (Liisa Coit, pers. com.).

Good lighting is also essential for the nursery tanks. The fry must be able to see the tiny organisms they live on clearly in order to feed efficiently. Use ”Daylight” fluorescent tubes or the equivalent and leave them on for a minimum of 14-17 hours a day, since the fry need to eat for at least 14 hours everyday (Vincent, 1995c).

Since the nursery tanks have limited filtration, daily water changes are needed in most systems to maintain water quality and keep up with the metabolic wastes and oxygen demands of several dozen baby sea horses and the thousands of brine shrimp needed to feed them (Giwojna, Jan. 1997). When the fry are well fed, defecation is amazingly rapid, with each newborn producing an average of one fecal pellet every 25-30 minutes (Herald and Rakowicz, 1951). The best way to perform the necessary maintenance is to use a length of airline tubing to siphon off the bottom of the nursery tanks a minimum of twice a day (morning and evening are ideal for this; Giwojna, Jan. 1997). Replace the water that was removed while siphoning with freshly mixed saltwater that has been pre-adjusted to the same temperature, pH and salinity as the rearing tank. Change about 10-20% of the water each time you siphon the bottom, so that a total of at least 25-50% of the water in the nursery tanks is exchanged every day (Giwojna, Jan. 1997).

Blacking out the top 2/3 of the aquarium and using side lighting or bottom lighting are techniques that are often used to help keep pelagic seahorse fry away from the surface, but there are many other (and better) nursery tank designs such as kriesels/pseudokreisels and in-tank nurseries that are more efficient at preventing surface huggers and floaters.

If you contact me off list, Glenn, I will be happy to provide you with much more detailed information on rearing newborn seahorses and the type of nursery tanks that are most suitable for this purpose (the files are a bit too large to post on a forum such as this). You can reach me at the following e-mail address:

[email protected]

Best of luck with the newborns, sir!

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

Dear Kayle:

I would be very happy to help you out with your new seahorse project, and I’ll do my best to answer your initial questions one by one below:

1. Is a tank height of 18 inches too low? I currently have a 24x24x18 tank I would like to use. I seem to get mixed opinions on this, and figured who better to ask then the people who actually bred the seahorses I want to get. Some say they have kept happy seahorses that bred in a tank only 16 inches high, and others say don’t go less than 24 inches.

I prefer taller tanks for seahorses for a couple of reasons, Kayle. In general, an aquarium at least 20-inches high is desirable (but not mandatory) when keeping the greater seahorses. They need the vertical swimming space to perform their complex mating ritual and successfully complete the egg transfer, which is accomplished while the pair is rising through the water column or drifting slowly downwards from the apex of their rise. If the aquarium is too shallow, eggs will be spilled during the transfer from the female to the male’s brood pouch, and mating becomes increasingly difficult or impossible below a certain minimum depth. A tall aquarium can also help protect the seahorses from depth-related health problems such as bloated pouch and certain forms of Gas Bubble Disease.

But an aquarium of 18 inches tall can certainly make a suitable seahorse habitat as long as you provide optimum water quality at all times and provide your ponies with good care.

2. I would like to keep some seahorse safe corals (gorgonians, zoas, mushrooms, and things of that nature that don’t sting. And nothing that needs intense light, as I read the ponies don’t like extremely bright light. Do you think the Blastomussa or Acanthastrea coral would fall under the safe category and not harm/sting them?

In general, seahorses do well with virtually all of the soft corals, Kayle. But you have to be more careful with the hard or stony corals since many of them have nematocysts that can produce painful stings to seahorses. The STS stony corals are much safer in that regard than the LPS stony corals.

For example, this is what I typically advise home hobbyists who want to keep seahorses in a modified reef systems with suitable live corals, Kayle:

<Open quote>
Live corals are a different matter altogether, and you must observe some special precautions when selecting corals for a seahorse tank. Here are some suggestions regarding what specimens do well with seahorses and which should be avoided, if you will be keeping live corals with your ponies or maintaining a reef biotype for them:

Seahorse-Proofing the Reef Tank

When designing a reef tank that will include seahorses, one must anticipate the different ways they might be injured in such a setup and then take precautions to prevent them from coming to harm. The process of rendering your reef system seahorse safe is much like the measures new parents take to childproof their house when they are expecting their first child. Intake tubes for the filters should be shielded, siphon tubes should be equipped with filter baskets or screens, and so on…

For instance, when powerful water movement is combined with overflows, there is a risk that seahorses could become pinned against an overflow or even go over it (Delbeek, Oct. 2001). Therefore, in the seahorse reef, overflows must be baffled and/or screened off, or the water flow should be adjusted sufficiently to prevent that from happening.

Likewise, although seahorses have no problem with strong currents in the wild, in the confines of aquarium, it is possible for them to come in contact with stinging corals if they are struck by a sudden powerful wave or surge, or are overwhelmed by a strong, unexpected current (Delbeek, Oct. 2001). The hobbyist needs to take this into consideration when placing water returns and corals in the seahorse reef (Delbeek, Oct. 2001). If possible, keep the water currents steady and unvarying so the seahorses can establish holding areas in the sheltered spots and low flow zones without getting blindsided by unpredictable currents.

One good way to accommodate both the needs of corals that prefer brisk currents and the seahorse’s need for slack-water retreats is to create tall rock formations a foot or two down current from the strongest water flows to intercept and deflect or divert that strong flow of water, creating eddies and slack-water zones where there is relatively little water movement down current. Seahorses will hold in these low flow areas when they want to move away from the current, so it’s a good idea to position convenient hitching posts in the lee or down-current side of such formations.

Another excellent way to accomplish the same thing is to use small powerheads to create and direct current wherever needed. A properly positioned powerhead can thus bathe your prized Acropora formations in a brisk water stream precisely without generating too much water movement elsewhere in the aquarium. Just be aware that powerheads can become death traps for seahorses if their intakes are not properly shielded or screened off, and take the necessary precautions (Delbeek, Oct. 2001). Carefully conceal the intakes amidst the rockwork where they will be completely inaccessible to seahorses, otherwise shield them, or screen them off with a sponge prefilter.

In short, the hobbyist who wants to keep seahorses in a reef system must be willing to make some concessions and modifications to accommodate their special needs nonetheless. For example, the reef keeper must be willing to limit himself to corals and invertebrates that meet the following criteria:

1) Avoid any stinging animals with powerful nematocysts. This means fire corals (Millepora spp.) and anemones should be excluded from the seahorse reef, and any corals with polyps that feel sticky to the touch should be used with discretion and only after careful planning. When a seahorse brushes up against them or attempts to perch on them, the nematocysts or stinging cells of these animals can penetrate the seahorse’s skin and damage its integument. Needless to say, this causes pain and discomfort and can leave the seahorse vulnerable to secondary bacterial and fungal infections, which may take hold at the site of injury. Short polyped stony (SPS) corals are generally fine, but large polyped stony (LPS) corals should be regarded with caution, as discussed in more detail below.

2) Water movement and circulation must be managed as previously described. Corals that require powerful surge or overly strong water currents could overtax the limited swimming ability of Hippocampus unless slack water areas the seahorses can retreat to when needed are also provided.

3) The corals must be able to withstand being used as hitching posts by the seahorses from time to time; that is, they cannot be so delicate that having a seahorse’s grasping tail anchored around them could cause them any harm. For instance, soft corals may retract their polyps when a seahorse perches on them. This can be harmful to their health if it becomes a chronic problem, because many corals rely on their polyps to absorb light and convert it to energy via photosynthesis. Be sure to watch any soft corals and hermatypic corals to make sure they are not closed up for extended periods. Normally, they adjust to the seahorses’ presence and unwelcome attention after a while, and remain contracted only briefly after each contact. After repeated exposures to grasping tails, each such incident elicits a weaker response, so they tend to extend their polyps sooner and sooner after being disturbed (Delbeek, Oct. 2001).

4) Avoid Tridacna clams and similar bivalve mollusks. Sooner or later a seahorse will perch on them with its tail between the valves and the clam’s powerful adductor muscle will clamp down on it like a vise. At best this will be a very stressful experience for the unfortunate seahorse, since it can be the devil’s own business trying to persuade the stubborn mollusk to release its struggling victim! At worst, it can result in serious injury or permanent damage to the seahorses tail (Giwojna, unpublished text).

5) Beware of unwanted hitchhikers that may have come in on your live rock unbeknownst to you and which can harm seahorses, such as fireworms, mantis shrimp, or Aptasia rock anemones. When setting up a reef system for seahorses, it’s a wise precaution to pre-treat your live rock with a hypersaline bath to drive out such pests beforehand because they can be very difficult to remove or eradicate once they make themselves at home in your aquarium (Giwojna, unpublished text).

As long as the specimens you are considering for your seahorse reef satisfy these requirements, anything goes! Some of the good and bad candidates for such a reef system are discussed below:

Seahorse-Safe Corals

Soft corals have very little stinging ability and generally make good choices for a modified mini reef that will include seahorses (Delbeek, Oct. 2001). This includes most mushroom anemones (corallimorpharians). However, as Charles Delbeek cautions, “One notable exception is the elephant ear mushroom anemone (Amplexidiscus fenestrafer). This animal is an active feeder on small fish and will envelope them whole with its mantle then slowly digest them by extruding its digestive filaments into the space created. No small fish are safe with these animals in the tank (Delbeek, Oct. 2001).”.

Hippocampus also does very well with zooanthids and colonial polyps in general. But the hobbyist must be sure to observe a couple of precautions when handling the zoanthids and placing them in your aquarium.

First and foremost, many of the commonly available Zooanthus (button polyps) and Palythoa (sea mats) species contain a very toxic substance in their mucous coat known as palytoxin, which is one of the most poisonous marine toxins ever discovered (Fatherree, 2004). Palytoxin can affect the heart, muscles, and nerves, resulting in paralysis or possibly even death, and many hobbyists have reported numbness, nausea and/or hallucinations after merely touching these corals (Fatherree, 2004). When you handle zoanthids and palythoans, you cannot help picking up some of their protective slime on your fingers, and so much as rubbing your eye, picking your nose, or a small cut on your finger can be enough to land you in the hospital. When handling Zooanthus are Palythoa species, it’s very important to wear disposable latex gloves, avoid touching your mouth or eyes, and carefully dispose of the gloves immediately afterwards (Fatherree, 2004).

Secondly, zoanthids and other soft corals such as mushrooms may wage border battles if you place them in close proximity to each other (and the zoanthids almost always lose out to the mushrooms in these skirmishes). So be sure to allow adequate space between the colonies. Some rapidly growing Zooanthus colonies can be aggressive to soft and stony corals alike as they rapidly spread over the rockwork, but in general they are quite peaceful, and you can always slow down their rate of growth by reducing the nutrient loading in the aquarium.

Other low light corals that should be suitable for a seahorse reef include genera such as Cynarina, Scolymia, as well as non-photosynthetic gorgonians such as Subergorgia and Didogorgia, and perhaps wire corals such as Cirripathes spp. (Delbeek, Nov. 2001).. However, supplemental feedings of zooplankton may be required to maintain these corals in good health.

The hard or stony corals fall into two categories depending on the size of their polyps. The small polyped stony (SPS) corals have tiny polyps that extend out of minute openings in the stony skeleton, and generally have weak stings that should not pose a threat to seahorses. Depending on conditions in the tank, SPS corals such as Acropora, Montipora, Pocillipora, Porities, Seriatopora and Stylophora can be tried freely at your discretion (Delbeek, Oct. 2001).

The large polyped stony (LPS) corals, however, are generally best avoided altogether. These include genera such as Catalaphyllia, Cynarina, Euphyllia and Trachyphyllia that have large fleshy polyps which often have tentacles equipped with powerful stinging cells. The Euphyllia and Catalaphyllia have the most powerful nematocysts among the LPS corals, and can deliver stings that are stronger than most anemones (Delbeek, Oct. 2001).

Some of the soft corals and stony corals that generally do well with seahorses in a modified reef tank are listed below. (By no means is this intended to be a comprehensive list, but rather just a few examples of suitable corals to serve as general guidelines when stocking a reef tank that will house seahorses):

Finger Leather Coral (Lobophyton sp.)
Flower Tree Coral – Red / Orange, (Scleronephthya spp.)
aka: Scleronephthya Strawberry Coral, or Pink or Orange Cauliflower Coral
Christmas Tree Coral (Sphaerella spp.)
aka: the Medusa Coral, Snake Locks Coral, or French Tickler
Cauliflower Colt Coral (Cladiella sp.)
aka: Colt Coral, Soft Finger Leather Coral, Seaman’s Hands or Blushing Coral.
Toadstool Mushroom Leather Coral (Sarcophyton sp.)
aka: Sarcophyton Coral, Mushroom, Leather, or Trough Corals.
Bullseye Mushroom Coral (Rhodactis inchoata)
aka: Tonga Blue Mushroom, Small Elephant Ear Mushroom (rarely)
Clove Polyps (Clavularia sp.)
Stick Polyp (Parazoanthus swiftii)
Green Daisy Polyps (Clavularia sp.), Indonesia
Orange & Green Colony Button Polyps (Zooanthus sp.), Fiji
Pulsing Corals (Xenia spp.)
Red Ricordea (Ricordea sp.), Indonesia, occasionally Solomon Islands
Lavender Hairy Mushroom (Actinodiscus sp.), Tonga
Pimpled Mushroom (Discosoma sp.), Indonesia
Purple Gorgonians

Lighting for a Seahorse Reef

If at all possible, metal halides should be avoided for a reef tank that will include seahorses. In addition to providing high-intensity lighting, the metal halides also tend to generate a lot of heat, and as you know, heat stress can be very detrimental to seahorses. Most of the subtropical/tropical seahorses do best at temperatures of around 73°F-75°F (23°C-24°C); so avoiding temperature spikes above 80°F (27°C) is very important. This can be very difficult to manage with metal halide lighting. In addition, seahorses don’t like excessively bright light and they may go into hiding, seeking shaded areas amidst the rockwork, if the lighting is too intense for their comfort level. And the seahorses won’t look their best and brightest under metal halides because they will produce excess melanin (black pigment) in order to protect themselves against the harmful ultraviolet radiation they associate with intense light, and darken as a result. For instance, Jorge Gomezjurado reports “…I have exposed yellow seahorses to strong metal halide and they have turned black in few hours.” So it would be a shame to display brightly colored seahorses under metal halide lighting in a small, close system aquarium.

All things considered, power compact lighting or LEDs with medium intensity are a better alternative for a seahorse reef. I prefer the power compacts because they allow me to provide my seahorses with a natural day/night period that includes twilight periods at “sunrise” and “sunset.” To accomplish this, I like the power compact (PC) light fixtures that include two tubes — one actinic and one daylight fluorescent — with dual ballasts so that each ballast can be placed on a separate automatic timer. I like to have the bluish actinic come on before the daylight tubes and stay on after the daylights go off, thereby providing a simulated dusk and dawn (Giwojna, unpublished text). This is important for seahorses since they conduct most of their courting and breeding in the early morning hours under twilight conditions. It’s a neat effect and fish and invertebrates can then anticipate “lights out” rather than being plunged into total darkness at night or suddenly thrust into bright light in the morning. I also adjust the timers to lengthen or shorten the daylight periods in accordance with the changing seasons. I find that maintaining a natural cycle this way aids reproduction (Giwojna, unpublished text).

Basically, I find PC lighting to be a good compromise for a seahorse system. Power compacts provide plenty of light for macroalgae or the seahorse-safe soft corals in a modified reef system without being too bright or generating too much heat, and the dual ballast system allows for a natural day/night rhythm that changes with the seasons. The resulting dusk and dawn facilitate courtship and help the seahorses maintain a natural reproductive cycle (Giwojna, unpublished text).

Although they are very costly, system such as the Solaris LED Illumination Systems are another good option for a seahorse reef. The Solaris LEDs can provide the spectrum of light and intensity needed by light-loving corals without the same concerns regarding overheating that make metal halides undesirable, and that’s a huge plus for the seahorse keeper. Aside from generating less heat, they also provide very considerable energy savings and the longevity of the LED is also superior to metal halide lamps. Best of all, the flexibility and adjustability of the Solaris LED Illumination System allows you to independently set the lights to duplicate sunrise, daylight, cloud cover, sunset, and even the lunar cycle. They certainly are very expensive, but they have some wonderful advantages over the conventional metal halide lighting, particularly for seahorses. However, because of the cost factor, I prefer PC lighting for a seahorse tank with live corals myself.

Of course, for seahorse keepers who do not have live corals in their corrals, standard fluorescent bulbs or tubes are more than adequate. For all intents and purposes, you really can’t go wrong no matter what lighting system you chose as long as you avoid overheating and provide both shaded areas where your seahorses can escape from light altogether and well-lit areas where they can bathe in the light as they please.

One good way to accomplish that is to keep the coral and inverts that require stronger lighting at one end of the tank, which is brightly illuminated, and keep the other end of the tank shaded to accommodate the seahorses, reserved for corals that don’t need high-intensity lamps. If need be, you can also provide shaded areas by positioning sections of aluminum foil atop your aquarium that are the right size and shape to cast shadows where you want them below. You will find your seahorses will move into and out of the light often, seeking the comfort level that suits them at the moment.
<Close quote>

And this is what Charles Delbeek has to say about keeping seahorses in reef systems:

<Open quote>
There has been a lot of interest lately in keeping sea horses in reef aquaria. Although it is possible to do so, there are some things that need to be taken into consideration. Most reef tanks that house corals also have a great deal of water movement. When combined with overflows, it is not uncommon for sea horses to be trapped against or even go over, overflows. Powerheads are also often used and can be death traps for sea horses if the intakes are not properly screened off. To keep sea horses in reef tanks one really must foresee all the possible ways that they could be injured and to take precautions against this happening.

Many corals are powerful stingers, but these belong mainly to the stony coral families. Most soft corals have very little stinging ability and will not harm sea horses. However, since sea horses can grasp onto soft corals with their tails they can cause the coral to retract its polyps. This can be a problem if the coral relies on its polyps to capture light to provide the energy it requires to survive. Fortunately in most cases, the coral will habituate to the constant irritation caused by the sea horse and will not retract its polyps as frequently as in the beginning. The observant aquarist should keep an eye on their soft corals to insure that they are not remaining closed for long periods of time.

In the case of stony corals there are two main groupings to be considered. The small polyped stony (SPS) corals consist of genera that have small polyps that extend out of very small openings in the skeleton. These would include genera such as Acropora, Montipora, Pocillipora, Porities, Seriatopora and Stylophora. These SPS corals are generally considered to be weak stingers and should not irritate sea horses very much. However, the same precaution I mentioned for soft corals also applies to SPS corals. The second major grouping are the large polyped stony (LPS) corals. These include genera such as Catalaphyllia, Cynarina, Euphyllia and Trachyphyllia that have large fleshy polyps often with tentacles that can have powerful stinging cells. Of these the Euphyllia and Catalaphyllia are the strongest stingers, and any sea horses placed into tanks with these corals should be carefully observed.

Despite what many people think, sea horses are quite effective swimmers and can hold their own in strong currents. However, in the confines of an aquarium, it is not impossible for them to come into contact with stinging corals if suddenly caught in a very strong current. The aquarist needs to take this into consideration when placing water returns and corals in the aquarium. People have been keeping fish with corals for several years now and the instances where fish have been taken by corals are few and far between, but it does happen occasionally. Sea Horses, like any other fish, have a natural ability to avoid most powerful stinging corals, and the slightest touch is enough to reinforce this natural avoidance behaviour.

Other invertebrates that sea horses should do well with include zoanthids, corallimorpharians (mushroom anemones), sponges, sea cucumbers, shrimp and the smaller detritus or algae feeding snails, worms and crabs. One notable exception is the elephant ear mushroom anemone (Amplexidiscus fenestrafer). This animal is an active feeder on small fish and will envelope them whole with its mantle then slowly digest them by extruding its digestive filaments into the space created. No small fish are safe with these animals in the tank.

Charles Delbeek
<close quote>

Okay, that’s the quick rundown on keeping seahorses in a modified reef tank that will include live corals, Kayle. Having explained all of the above, I should also point out that Mustangs or the Sunbursts (Hippocampus erectus) often thrive in suitable reef tanks, where they benefit from the optimum water quality, natural surroundings, and abundant copepods and amphipods in typical well-established reef systems.

3. I’m pretty sure that you guys breed at 75 degrees. Yet on your care sheets there is a range given 68F – 82F (Optimum temperature 75 – 78F) for the H. Erectus as an example. So I would assume I could safley keep my water at 76 – 77 safely or would that increase the risk of disease?

Yes, that’s correct – tropical Ocean Rider seahorses are maintained at a stable water temperature of 75°F.

The seahorses at the Ocean Rider aquaculture facility in Hawaii do just fine at a temperature of 76°F-78°F, but in the home aquarium, they will be experiencing much different conditions in a small, close system tank that is subject to considerable temperature variations. The average aquarist’s seahorse tank is relatively small and uses artificial saltwater and artificial lighting, and the lighting is a heat source that can raise the temperature of the small aquaria significantly over the course of the day. More importantly, the smaller aquariums can experience harmful temperature spikes during summertime heat waves. In my experience, the home hobbyist should strive to maintain stable water temperatures in the 72°F-75°F range in order to compensate for these other factors. In general, as a rule, all seahorses do better at the lower end of their acceptable temperature range then at the upper end of their comfort zone, particularly in the small, closed system aquariums of the home hobbyist.

As you know, Kayle, heat stress is extremely debilitating for seahorses and, in my experience, it is associated with more disease problems and mortalities in the home aquarium than any other factor. There are number of reasons for this. For one thing, elevated temperatures can have a very detrimental effect on the immune system of fishes. This is because many of the enzymes and proteins involved in their immune response are extremely temperature sensitive (Olin Feuerbacher, pers. com.). Some of these protective enzymes can be denatured and inactivated by an increase of just a few degrees in water temperature (Olin Feuerbacher, pers. com.). So when seahorses are kept at temperatures above their comfort zone, their immune system is compromised and they are unable to fend off diseases they would normally shrug off.

At the same time heat stress is weakening the seahorse’s immune response, the elevated temperatures are increasing the growth rate of microbes and making disease organisms all the more deadly. Research indicates that temperature plays a major role in the regulation of virulence genes (Olin Feuerbacher, pers. com.). As the temperature increases, virulence genes are switched on, so microorganisms that are completely harmless at cooler temperatures suddenly become pathogenic once the water warms up past a certain point. Thus both the population and virulence of the pathogens are dramatically increased at higher temperatures (Olin Feuerbacher, pers. com.).

This is true of Columnaris and certain types of Vibrio. At cool temperatures these bacteria are relatively harmless, but at elevated temperatures they become highly contagious, virulent pathogens that kill quickly. Neil Garrick-Maidment, director of the Seahorse Trust in the UK, reports that he stopped a deadly outbreak of Vibrio among his Hippocampus capensis dead in its tracks and cured the seahorses simply by cooling their aquarium down to 18°C (64.4°F) for a period of weeks. The bacteria simply no longer presented a problem at that temperature.

Here’s what Olin Feuerbacher reports regarding the effect of temperature on bacterial infections. Olin is a marine biologist who is now a Molecular Biologist and a member of the research staff at the Arizona Genomics Institute, and who runs a small aquaculture business raising clownfish, gobies, a bit of coral, and all sorts of odd food items including a lots of pods, microalgae, etc. He is also a seahorse keeper and has done a lot of research in tropical diseases. He is a grad student working on marine microbiology, mainly ocean borne human pathogens, and his specialty has been the Vibrio bacteria!

In short, Olin really knows his stuff when it comes to this sort of thing. Here are his thoughts on bacterial infections in seahorses:

Quote:
They typically start as a secondary infection after either mechanical damage or parasites or cnidarian stings. Once established, they are difficult to control. This is due in part to the fact that they are typically normal flora in all tanks. They are generally benign until they get an opportunity to invade. As for the importance of avoiding heat stress when it comes to bacterial infections (or the value of maintaining reduced temperatures when fighting a bacterial infection), this is what he has to say:

It is interesting that you mentioned the elevated
temperatures. I think this is a critical factor in a
number of ways. First, elevated temperatures can have
many adverse effects on the immune status of many
organisms. Many of the enzymes and proteins involved
in an immune response are very temperature sensitive.
When studying an outbreak of vibriosis in echinoderms
during an El Nino event in the Sea of Cortez, I found
that several defensive enzymes in the echinoderms were
inactivated by a rise of only a few degrees in water
temperature.

In addition to the effects on the hosts, water
temperature may have very significant effects on the
pathogens as well. First, elevated temperature will
obviously increase the rate of microbial growth.
Perhaps more importantly, recent research has
implicated temperature as a major factor in the
regulation of virulence genes. When in the cooler
pelagic environment, a bacteria wants to conserve
energy, so virulence genes will not be expressed since
there is probably no host. However, in warmer temps,
these genes can be turned on resulting in pathogenesis.

This is especially true for bacteria such as the
Vibrios which exist both as normal aquatic flora and as
pathogens in many mammalian species with our nice warm
digestive tracts etc. One particularly interesting
study showed that the coral pathogen Vibrio strain AK1
was completely benign, despite heavy colonization, in
corals at one temp (I forget exactly what, I think it
was about 25C), but when temperature was raised by 3
degrees, all of the virulence genes in the Vibrio’s
pathogenicity island were turned on. This resulted in
severe infection and rapid death of the corals. Bad
news for aquarists, but I still think this kind of gene
regulation is really cool!
Olin

So raising or dropping the water temperature just a few degrees can make a huge difference. Likewise, here are Neil Garrick-Maidment’s observations on the importance of water temperature when treating a Vibrio infection:

[Quote]
I am not sure if it is of any help but I recently had a problem with vibriosis
in Hippocampus capensis coupled with a couple of gas bubbles in the end of the
tail. Having tried a number of treatments in the past that havn’t worked I took
a slightly more drastic approach this time and dropped the temperature from 23°C (73.4°F) down to 18°C (64.4°F) having first isolated the infected animals into a separate tank. I then left them like this for 4 weeks after which I increased the
temperature slowly up to 21°C (70°F), which it still is. After the second week
the vibriosis had gone completely (and has not returned) and the gas bubbles
were gone after the third week. In all the time the temperature was low the
animals reduced their feeding and it has now increased with the raising of the
temperature and they since gone on to have two broods of fry.

Best wishes,

Neil Garrick-Maidment
Seahorse Project Co-ordinator

Aside from the detrimental effects heat stress has on the immune system of seahorses and the virulence of pathogens, it also has an adverse affect on the breathing of seahorses and is responsible for many deaths by asphyxiation. Elevated water temperatures increase the metabolism of seahorses, and therefore their consumption of oxygen, at the same time that the rise in temperature is reducing the amount of dissolved oxygen the water can hold. That creates a dangerous situation for seahorses and may well result in respiratory distress and rapid, labored breathing.

Seahorses are more vulnerable to the low O2/high CO2 levels associated with heat stress than most fishes because of their primitive gills. Unlike most teleost (bony) fishes, which have their gills arranged in sheaves like the pages of a book, seahorses have rudimentary gill arches with small powder-puff type gill filaments. Seahorses are said to have “tufted” gills because they appear to be hemispherical clumps of tissue on stems. Their unique, lobed gill filaments (lophobranchs) are arranged in grape-like clusters and have fewer lamellae than other teleost fishes. Because of the difference in the structure and efficiency of their gills, seahorses are thus especially vulnerable to low oxygen levels and asphyxia.

In short, Kayle, if you can maintain a stable water temperature of 76°F-77°F, the seahorses will be well within their comfort zone, but it’s very important to prevent the water temperature from approaching 80°F or above for any length of time for the reasons discussed above.

Best of luck with your new seahorse setup, Kayle.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

Dear Tamra:

It’s difficult to say with any degree of certainty what the two white balls on the hypersensitive tip of Tigger’s tail may be that caused so much pain and stress when you removed them, but I would be happy to share my thoughts on the matter with you.

For starters, let’s review some of the possibilities. A suspicious ball or bump on a seahorse could be a granuloma. For example, pyogranulatomous cysts are often described as pimplelike bumps or nodules and can be symptoms of serious bacterial infections such as white tail disease.

Or the white balls could be bacterial or fungal lesions related to the white tail disease that Tigger has been battling, Tamra. Such lesions often protrude above the surrounding tissue like a scar does.

Like all fish, seahorses do occasionally develop various granulomas, tumors and fibrosarcomas associated with certain diseases or the aging process, so that’s a possibility that must be considered whenever there are any suspicious growths detected on a pony, although I think that’s very unlikely in this case, Tamra. Often these growths are benign and harmless, but they can also develop malignant neoplasms and cancerous tumors on rare occasions. However, Tigger seems way too young to have developed any such tumors, Tamra.

Rather, it could be that the two white balls are due to a harmless viral infection (e.g., Lymphocystis or papilloma). Many such growths are harmless, just like the warts we occasionally develop. Lymphocystis results in white-ish to grayish cauliflower-like growths that sprout up suddenly. They appear most often on the fins but may also develop on other parts of the body. Again there is no treatment, but Lymphocystis is harmless and the growths will often disappear as suddenly as they appeared.

Likewise, it’s not uncommon for marine animals to contract wartlike papilloma virus infections these days, so it’s possible the white balls could simply be papillomas. If that’s the case, a wart-like viral infection such as papilloma will not respond to any readily available medications and I can suggest no treatment, which is not really a problem since they are essentially harmless and there is no need to intervene in any case…

Most likely, the two white balls are related to Tigger’s white tail disease, which is of course a far greater problem at this point and the likely reason that he has lost his appetite and appears to be going downhill.

Since the white tail disease responded well to the oral antibiotics (KanoPlex and NeoPlex soaked in garlic guard), Tamra, I certainly see no reason why you can’t administer another regimen of these medications in the same manner. The Garlic Guard does act as an appetite stimulant, which may encourage him to eat the medicated Mysis…

For what it’s worth, I also sent you information on other medications that are sometimes useful when treating white tail disease or tail rot as an attachment to an email, Tamra. Hopefully, one of the medications discussed in the attached information may be helpful in addressing Tigger’s tender tail and white tail disease.

Neosporin can be applied as a topical treatment, but it is likely to be stressful and painful to Tigger to apply it to his hypersensitive tail, so I don’t know how helpful that would be…

If you do decide to set up your hospital tank, Tamra, then there is one treatment that could possibly be helpful in addressing the two white balls that you removed, which would involve treating your hospital tank with Instant Ocean Lifeguard.

Here’s the rundown on the Instant Ocean Lifeguard and how to administer it properly. In a case like this, when it’s unclear whether you are dealing with a bacterial infection, a fungal problem, or a mixed infection, treatment with Instant Ocean Lifeguard in your hospital tank or quarantine tank is a good place to start. Instant Ocean Lifeguard is easy to use, inexpensive, and often available at local fish stores, including Petco and Petsmart retail stores so it is easy to obtain, allowing you to begin treatment promptly, which is very important for obtaining good results. The product may have a variety of different names depending on where you purchase it, including Instant Ocean Lifeguard, Instant Ocean Lifeguard Saltwater, or Instant Ocean Lifeguard All-in-One Marine Remedy. It is effective in treating mouth and fin rot, and white tail disease/tail rot is caused by the same sort of bacteria that cause fin rot and mouth rot and other fishes.

Here is some more information explaining the type of problems Instant Ocean Lifeguard is often effective in treating and how to use the medication:

<open quote>
Instant Ocean Lifeguard

Instant Ocean Lifeguard Saltwater tablets with HaloShield® attack a broad range of external fish diseases in saltwater aquariums including bacterial, fungal, viral, and parasitic. It’s HaloShield®, a revolutionary non-antibiotic agent, that makes LIFEGUARD pre-measured tablets so tough on harmful disease-causing microorganisms.

It is made by Instant Ocean, it is specifically for marine use and treats the following: ick, oodinium, fungus,milky or shedding slime,bacterial gill disease, mouth and fin rot, clamped or torn fins, and ulcers.

Safeguard tanks with LIFEGUARD! One tablet treats 10 gallons of water, recommended treatment is for five days.

Keep your aquatic pets healthy and fit with Instant Ocean LIFEGUARD All-In-One Marine Remedy. This therapeutic treatment is ideal for marine fish and treats clinical signs of diseases in its earliest stages. HaloShield® eliminates disease-causing microorganisms, and each tablet is premeasured for precise dosage and dissolves easily in water. Instant Ocean Lifeguard Saltwater is effective against marine Ick & Oodinium.

Ideal for use with marine fish
Treats a range of diseases, including bacterial, fungal, viral and parasitic conditions
HaloShield destroys disease-causing microorganisms
Effective against marine ick and oodinium
Tablets are premeasured and dissolve easily
Add 1 tablet per day to each 10 gal. of water
Made in the USA

Active ingredients: 1-chloro-2,2,5,5-tetramethyl-4-imidazolidinone.

Directions
Before treatment, remove filter carbon and turn off proteins skimmer and UV sterilizer. Add one tablet per day to each 10 US gallons of aquarium water using the enclosed treatment apparatus. Use treatment for 5 consecutive days, at 24-hour intervals. For best results, after 5-day treatment is complete, wait 24 hours (day 6), then return activated carbon and turn on UV sterilizer. Perform a 25% water change using a dechlorinator and a bacteria-enzyme to condition aquarium water. To treat smaller aquariums, break tablet along score lines. Each 1/4 tablet treats 2-1/2 US gallons.

Keep out of reach of children. For aquarium use only. Not for use on food fish. Not suitable for invertebrates or newly set up aquariums. Some macroalgae may show sensitivity. Use only as directed. Do not overdose. If overdose occurs, add carbon or dechlorinator as directed for immediate neutralization.

Available in a 16 pack

Ingredients:
1-chloro-2,2,5,5-tetramethyl-4-imidazolidinone
<close quote>

Okay, that’s the scoop on the Instant Ocean Lifeguard, Tamra. It is not reef-safe or safe to use with the invertebrates, so you can’t use it in your main tank – only a quarantine tank or hospital tank. Also, be sure to keep the treatment tank well aerated since you must not operate your protein skimmer during the five-day treatment.

Good luck.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

Dear Jenn:

I’m very sorry to hear about the problems you have been having with your female seahorse, Jenn. It sounds like you did a wonderful job of nursing your pony through a case of gas bubble disease, and you certainly addressed that problem correctly. Well done.

The behaviors you described bring a a few different things to mind. I don’t have a really clear idea of what is going on with your pony at this point, but I would be happy to share my thoughts on the matter with you.

For instance, you mentioned that your female had stopped eating and needed to be hand fed, and that it was crashing into things when returned to the main tank following treatment in your hospital tank. Those are things that suggest you could be dealing with temporary blindness.

Over the years I have encountered several instances of blindness in seahorses, Jenn. Two of them were the result of severe bilateral exophthalmia (commonly known as Popeye), which caused functional blindness and prevented the seahorses from feeding properly. In a few other cases, the apparent blindness was associated with high intensity lighting, so if your quarantine tank is brightly lit, the seahorse’s eyesight may have been impaired as a result.

In short, I know of a few seahorses that have developed blindness and it’s not as uncommon as you might expect. Some of the marine fish that are especially prone to this problem in captivity are lionfish, large angelfish of various species, seahorses, clownfish, and large puffers and porcupine fish.

In most of the cases I am familiar with, the blindness was caused by exposure to bright lighting under circumstances when there was no way available for the fish being displayed to seek shelter and get out of the light when they wanted. When that’s the case, the blindness is often temporary, and the affected fish’s vision can be restored by maintaining it in total darkness for an extended period of time. Apparently the complete absence of light is beneficial or therapeutic in some cases of blindness, and the affected fish are normally hand fed well they are recovering…

For example, this is what Robert PL Straughan (Saltwater Aquarium in the Home) reports regarding blindness in aquarium fishes, Jenn:

Blindness

“When a fish suddenly shows no interest in food, it may have gone blind. Excess light is usually the cause, especially when the fish is not given a dark hiding place in the aquarium where it can go once in a while. The fish may bump into coral or snap at food which it can feel or sense but cannot see, and prompt action must be taken to save your pet. You can usually see if the fish is blind by moving your hand quickly in front of the glass. If he shows no response even though you attempt to frighten him from the outside, and if he swims to the end of the aquarium and bumps into the glass or coral, then he is most likely blind. This does not necessarily have to be a permanent condition and it can usually be cured, with time and patience.

“First remove the victim to a separate aquarium, and cover the sides and top of the tank with cardboard to keep out most of the light. Since the fish is blind, it will have to be hand fed and this may be accomplished by holding the fish gently with one hand and forcing chunks of chopped shrimp into its mouth with the other. Usually, if the fish is tame, it will accept food eagerly in this fashion and if it does, it is well on the road to recovery. Usually when hand feeding a blind fish, it is best to handle the fish very gently so that it will not become excited, then release it equally as gently after the food has been placed well in its mouth. It will usually swallow the food and the whole procedure may be repeated until the fish has eaten his fill.

“If, after a week or so, the fish responds to light, remove one side of the cardboard so that the aquarium will be partly lighted. The fish may be returned to the regular aquarium after its sight has returned, but this time, it should given a good coral hiding place so that it can get completely out the light when it desires. This is a perfectly natural situation as anyone who has observed marine life on the reef can testify. The fish will swim out into the bright sunlight for brief periods of time and then periodically retreat to the dark seclusion of a coral ledge or other protection.

“Large Porcupine fish, Rock Beauties, and Angelfish, are especially susceptible to blindness from too much light, and can be blinded in a matter of hours if left in direct sunlight with no cover or protection. Also the Lionfish, Clownfish, Seahorse and any other fish which tend to stay out in the open, can be blinded if subjected to intense aquarium light.” This condition is often brought on, when fish are placed on public display. The lights are left on for long periods of time, and the fish are given no place to hide so that usually in a week or so, the fish are blinded.”
Robert P.L. Straughan, The Salt-Water Aquarium in the Home, A.S. Barnes & Company, 123-124.

So marine fish can be blinded by intense light if they have no opportunity to escape from the bright lighting for an extended period, and our prize ponies are among the fish that are most susceptible to this problem, Jenn. Seahorses with impaired vision stop feeding (they are of course visual hunters) and typically stop moving around since they cannot see where they are going to avoid obstacles.

However, from what I have gathered, the blind seahorses I know of all readily accepted handfeeding and seemed to realize that the hobbyist was trying to help them by offering food in this manner.

So if you have recently changed your aquarium lighting, especially if you have upgraded to high-intensity lighting such as metal halides for the sake of live corals or some such thing, it is possible that your female may have gone blind, Jenn. On the other hand, fish will blindly crash into objects and bang into the sides of the aquarium in a panic when they are frightened or startled, so your female seahorse may be able to see perfectly well. There is no way for me to determine that from afar…

Another possibility is that your female seahorse has an underinflated swimbladder and is suffering from negative buoyancy (the tendency to sink) as a result. Fish with an underinflated swim bladders always tend to stay at the bottom of the aquarium because it requires great effort for them to swim upwards. An underinflated gas bladder can happen as a result of stress and pH shifts during acclimation. Fortunately, that’s a problem that a seahorse can correct itself, using the gas gland in the lumen of its swim bladder to slowly add more oxygen to the swim bladder. This may take several days as the seahorse’s blood chemistry returns to normal and it gradually reinflates its swim bladder.

When seahorses are swimming and want to ascend, they will lift their heads and extend their tail out straight beneath them and hold it extended in order to shift their center of gravity and make it easier for them to rise. Likewise, when a swimming seahorse wishes to descend in the water column, it will tuck its head and curl its tail beneath it in order to shift its center of balance and make it easier to swim downward. The contorted body movements you describe and the unusual way your female is holding its tail could be an indication that it is struggling to swim normally due to an underinflated swimbladder, Jenn. If so, that’s merely a temporary problem that the seahorse should be able to resolve on its own.

On the other hand, if a seahorse that is holding its tail behind its body forming a “U” shape, that could be an indication that its tail is very tender and sensitive, and is often an early sign of tail rot or white tail disease, Jenn.

Such diseases begin with a loss of prehensility in the very tip of the tail (Giwojna, Oct. 2003). At this stage, the seahorses can grasp large objects just fine, but cannot take hold of slender objects with a small diameter (Leslie Leddo, pers. com.). Next the loss of prehensility spreads further up the tail and the seahorses begin to act as if their tails are very tender and sensitive. They will drape their tails over objects rather than grasping onto them and begin to drag their tails behind themselves, often arching the end of their tail upward in the shape of “U” (rather than the usual “J” or tight coil) as if to lift it off the ground and keep it from touching anything (Leddo, pers. com.).

This is usually when the tip of the tail becomes white and the loss of coloration starts advancing further and further up the tail (Giwojna, Oct. 2003). At this point, the discolored skin begins to flake or lift up and open wounds and ulcers develop on the most distal portions of the tail (Giwojna, Oct. 2003). The infection attacks the underlying tissues, and the tail is gradually eaten away, often all the way to the bone, exposing the vertebrae (hence the name Tail Rot). Survivors may end up missing the last few segments of their tail (Giwojna, Oct. 2003).

In short, you need to keep a close eye on your female at this point to make sure that it is not developing tail rot, Jenn. Many times tail rot is associated with heat stress, but your water temperature is excellent, which would seem to eliminate heat stress is a factor in this case. It would also be unlikely for a seahorse to develop tail rot after being treated with antibiotic therapy in your hospital tank, so I just can’t be sure of any sort of a diagnosis or prognosis with so little to go…

If you contact me off list at the following email address ([email protected]), I can provide you with additional information, Jenn. Please keep me updated on the progress of your female seahorse. Hopefully, she will soon settle down, begin eating and swimming normally again, and and be none the worse for wear following the episode of gas bubble disease.

Good luck.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

Dear Eve:

Personally, I favor the lower range of the optimum salinity for Hippocampus zosterae at around 1.019 simply because it’s possible that the lower salinity might help prevent some of the invertebrate pests that plague dwarf seahorses, such as hydroids, nematodes, and aiptasia rock anemones, from becoming established in your setup.

Here is a copy of my species summary on Hippocampus zosterae that will provide you with additional information about these pixie-like ponies:

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
Synonyms:
Hippocampus regulus
Hippocampus rosamondae
Maximum size: 2 inches (5.0 cm) in total length.
Climate: subtropical to tropical: 20° N to 30° N.
Distribution:
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.
Morphometrics:
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.

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 that quickly enough becomes alive as it’s overgrown by algae and inhabited by copepods, amphipods and myriad microfauna. It looks completely natural when surrounded by living, growing macroalgae, which is primarily how my dwarf tanks are decorated.

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 and Scarlet Reef hermit crabs (Paguristes cadenati) are the cornerstones of the clean-up crew in my dwarf tanks. The Scarlet Reef micro-hermits are colorful and interesting in their own right, and these harmless herbivores are the only hermit crabs I trust with my dwarf seahorses. A half dozen of the colorful Scarlet Reef crabs make nice additions for a dwarf seahorse tank, as do the Nassarius snails, which are very active, efficient scavengers that handle the meatier leftovers.

I do small weekly (15%-20%) or biweekly water changes of 10%-15% on my dwarf tanks, 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 dineson 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).

Along with the Volcano shrimp, Nassarius snails and Scarlet Reef hermit crabs (Paguristes cadenati) can serve as the cornerstones of the clean-up crew for dwarf seahorse tanks. The Scarlet Reef micro-hermits are colorful and interesting in their own right, and these harmless herbivores are the only hermit crabs I trust with my dwarf seahorses. A few of the colorful Scarlet Reef crabs make nice additions for a dwarf seahorse tank, as do the Nassarius snails, which are very active, efficient scavengers that handle the meatier leftovers.

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.

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.

Discussion:

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.

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. <http://www.fishbase.org/Summary/SpeciesSummary.cfm?id=3286&gt;

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.

Do you have a copy of Alisa Abbott’s guidebook (Complete Guide to Dwarf Seahorses) yet, Eve? That’s one book every Pixie owner and dwarf seahorse keeper should have on hand. I’ve proofed Alisa’s dwarf seahorse book for TFH publications and wrote the preface for it, and I highly recommend it!

Respectfully,
Pete Giwojna, Ocean Rider Tech Support

Aggressive pipefish

Dear tlskahan:

As you know, at the Ocean Rider aquaculture facility, the pipefish are raised together at high population densities from birth until they are ready to market. As juveniles, at least, they seem to very much enjoy the company of others of their kind and find reassurance in numbers.

In short, the Ocean Rider red banded pipefish (Doryrhamphus dactyliophorus) are normally very sociable and gregarious, and are becoming more so with every generation, since they are accustomed to living in close proximity with many others of their kind from the moment they emerge from their eggs until they reach marketable size and are shipped off to the home hobbyists.

But it is very difficult to sex juvenile banded pipefish because of the lack of a brood pouch. It is normally only possible to determine male and female when the pipefish are actively breeding and the male’s brood patch is ready for the eggs to be attached. There is simply no reliable way to determine the gender of the juvenile pipefish.

Although they are normally quite peaceful, on occasion, however, juvenile pipefish that are approaching sexual maturity, and which have been very friendly towards one another up until they matured, may occasionally become antagonistic if it turns out that they are both males. When you get two of the pipefish and they are both females, they typically get along very well and there is no aggression, and likewise, when they turn out to be a male and a female, courtship and mating is a typical result, rather than any sort of fighting. But, should the two pipes ultimately turned out to be two males, that is when there may be some sparring and fighting as they determine dominance.

In that event, providing your aquarium is large enough, the two pipefish can still happily coexist once they have determined which of them is superior to the other. I should think that your 60 gallon cube tank should be spacious enough for the two pipefish to get along together in the long run. But if the larger pipefish is so aggressive towards the smaller individual that the youngster is unable to feed in peace, then you may need to separate these two individuals to separate aquariums.

In the home hobbyists’ tank in which two of the pipefish are confined together in a relatively small space, there can be problems if both the individuals are males. Under those circumstances, as I mentioned above, there is a chance that the pipefish may indeed sometimes become hostile towards one another as they mature. When you are keeping a couple of juvenile pipefish together, and one of the pipefish become a mature female, they usually continue to get along very well. Even better, if the pair of pipefish turns out to be a male and female when they grow up, they will eventually become a bonded pair that reproduce.

But, of course, sometimes both of the pipefish will be males when they mature, and I think that’s the instance in which trouble sometimes ensues. I believe that, even when both types turn out to be male, many times they will continue to coexist in the aquarium without any open hostility, since one of the individuals will assert his dominance and then be unchallenged by the subordinate individual thereafter, allowing them to get along fine and each continue to get enough to eat at mealtime, etc., when the aquarium is large enough, at least.

Sometimes, however, they continue to compete and persist in fighting, sir, and those are the occasions where it is appropriate for the hobbyist intervene and separate the two individuals.

In a case like that, you may need to relocate the subordinate individual to one of your other aquarium systems, such as your well-established reef tank. But even in the worst case scenario, you will still have two healthy pipefish to add color and interest in your tanks, only they would be living in separate aquariums rather than together.

If you send me a quick email ([email protected]), I would be happy to send you a document with additional information regarding the red banded pipefish that you may find helpful, sir.

Best wishes with all your fishes, Tony!

Respectfully,
Pete Giwojna, Ocean Rider Tech Support