Dwarf Seahorses for a beginner

Dear hero:

In looking over your proposed setup, it is apparent that you have indeed done some advance research with regard to dwarf seahorses (Hippocampus zosterae) but it is also apparent that you still have much to learn about their aquarium requirements as well, and it was very wise of you to present your plans on a discussion forum such as this for feedback before you proceed.

It is clear from the aquarium you have selected, the type of filtration and water circulation you are planning on installing into the gutted Biocube, and the list of tankmates that you hope to keep that your intent is to design an aquarium system that will be good for live corals as well as dwarf seahorses, and I believe that is a fundamental flaw in your system. The fly in the ointment with the type of dwarf seahorse tank you hope to achieve, hero, is the issue of hydroids. Any aquarium that includes live sand and assorted live corals, and that will meet the feeding requirements of the dwarf seahorses, which require copious amounts of bite-size live foods (Artemia nauplii, larval copepods, larval Mysis, etc.) on a daily basis, is going to have chronic problems with the deadly hydroids and I just don’t see any possible way around that.

In the reading and research on dwarf seahorses you have done, hero, I know you must already be all-too familiar with the danger that hydroids present for these pint-size pigmy ponies, so please bear with me while I rehash the issue on this forum. This is what I normally advise seahorse keepers with regard to hydrozoans:

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

It can be very challenging to identify hydroids because there are about a zillion different species of hydrozoans and the different types have different characteristics and are often vary remarkably in appearance. There is considerable variation within the species as well, and the same type of hydroids can appear vastly different depending on the size of the colony and its stage of development, conditions in the aquarium, and their predominant diet. And, of course, the different stages of the life cycle of these amazing animals are so entirely different that they were long believed to be different types of cnidarians altogether, and different species names were often assigned to the same hydroid in different phases of its life cycle. Because they are so difficult to identify and are not easy to distinguished with the naked eye during their initial stages, hydroids often go undetected in nursery and rearing tanks until they begin to take a toll on the fry.

The typical hydroid colony has a stem with a variable number of polyps growing on it, and each of these polyps bears numerous tentacles that are liberally studded with knobby nematocysts (batteries of deadly stinging cells). There are many different kinds of hydroids and they appear in the aquarium in many different guises: many colonies are stalked; some have fingerlike projections, others look like tiny pink fuzzy balls or appear like cobwebs (the webbing kind usually spread along the bottom or grow on the aquarium glass along the substrate). The "snowflake" type of hydroids seem to be particularly common in aquaria, whereas other species look more like crystal chandeliers, and some species form bushy colonies as they grow that serve as microhabitats for Caprellid skeleton shrimp and other tiny crustaceans.

Even a large hydroid colony appears harmless to the naked eye of the untrained observer. It takes a much closer look to reveal the dreaded ‘droid’s lethal nature, as described below:

"Studying the colony under high magnification, one soon becomes lost in an extraordinarily complex, living world–a microcosm in which a beautiful but deadly ballet is conducted on a microscopic scale (Rudloe, 1971). Hungry polyps, some resembling snapdragons, others looking more like daisies or tulips, expand their knobby, translucent tentacles, slowly flexing and languidly waving them about, lulling the observer with their slow-motion ballet — until they abruptly and quite unexpectedly snap up a bit of planktonic life, stinging it, drawing it in with one violent contraction, digesting it, and then re-expanding like a blossoming flower to hunt again (Rudloe, 1971). There are many such polyps in a colony, hundreds of them, each of which is armed with many tentacles and countless nematocysts, and at any given moment, some of them will be dormant and still, some will be expanded and lazily casting about for prey (Rudloe, 1971), and still others actively feeding (Abbott, 2003)."

The feeding or nutritive zooids are the distinct individual animals in a hydroid colony that are responsible for capturing and digesting prey; as such, they bear the nematocyst-studded tentacles. But you need high magnification in order to appreciate the true beauty of living hydrozoans, or to differentiate between different species of hydroids, or to observe the zooids going about their deadly business.

Hydroids are insidious because they start out so small and insignificant, yet spread so quickly under ideal conditions (e.g., a nursery tank or dwarf seahorse tank receiving daily feedings of Artemia nauplii). Many species can spread asexually by fragmentation as a microscopic speck of the parent colony. All of the troublesome types have a mobile hydromedusae stage, which look like miniscule micro-jellyfish, and can spread sexually in this way as well (Rudloe, 1971). The mobile medusae swim about with a herky-jerky, pulsating motion and are often mistaken for tiny bubbles due to their silvery, transparent, hemispherical bodies (Rudloe, 1977). These tiny jellies often go unrecognized until they begin to settle and are discovered adhering to the tank walls. They will have a large "dot" in the middle of their bodies and smaller ones at the base of their nematocysts (Abbott, 2003). Both the polyp stage and the medusa stage sting (Rudloe, 1977) and are capable of killing or injuring seahorse fry. Multiple stings can kill the babies outright, but they are often only injured by the nematocysts, which damage their integument and leave them vulnerable to secondary infections. Many times it is a secondary bacterial or fungal infection that sets in at the site of the injury which kills the fry.

Once they find their way into a dwarf seahorse setup or nursery tank, hydroids can explode to plague proportions very quickly because conditions are ideal for their growth: perfect temperatures, an abundance of planktonic prey that is renewed every few hours, and a complete absence of predators.

When hydroids become a problem in the nursery or dwarf tank, there is a simple way to eradicate them and get the situation under control again:

Eliminating Hydroids

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

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

Because fenbendazole is essentially a de-worming agent, it will destroy any bristleworms, flat worms, spaghetti worms or the like. The FBZ or Panacur treatments are best administered to the live rock in a bucket or hospital tank before the LR is introduced in the main tank. Otherwise, the massive die-off of the worm population in the aquarium may require large water changes in order to prevent a dangerous ammonia spike! And after the treatment is completed, its a good idea to add a portion of newly purchased live sand to the system in order to help restore its normal diversity of fauna and microfauna again (Liisa Coit, pers. com.).

Fenbendazole does not have any adverse effects on biological filtration, but be aware that it is death to many Cnidarians besides hydroids. Mushrooms and related corals are generally not affected, but expect it to have dire effects on other corals (e.g., sinularias), polyps, gorgonians, and anemones. In general, any Cnidarians with polyps that resemble the stalked family of Hydrozoans are likely to be hit hard by fenbendazole, so don’t use this treatment in a reef tank!

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

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

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

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

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

In summation, if the aquarium with a hydroid problem will be housing live corals at some point, it would be best not to treat it with fenbendazole.
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Okay, hero, that’s the quick rundown on hydroids. An outbreak of hydroids is devastating to dwarf seahorses, which are sensitive to their stings, and an outbreak of the hydrozoans would be inevitable in the type of aquarium you are planning. Unfortunately, the one sure cure for eliminating the hydroids — treating the tank with fenbendazole (brand name Panacur) — would be deadly to the live corals, polyps, and featherdusters worms that you hope to keep in your aquarium. In other words, once the hydroids appear — which I believe would be sooner rather than later — you would face the dilemma of either sacrificing the dwarf seahorses for the sake of the live corals and featherdusters or sacrificing the live corals and featherdusters for the sake of the dwarf seahorses.

So, before you learn about the harmful effects of hydroids in a dwarf seahorse tank the hard way, hero, I suggest that you rethink your fundamental aquarium design. This is what I propose: I have a great deal of information about dwarf seahorses available off list — informative articles, species summaries, descriptions of all sorts of aquarium setups that have proven to be very successful with dwarf seahorses, detailed information on their natural history, breeding and rearing, compatible tankmates, diverse food sources for dwarves, etc. — in files that are much too large to be presented in a simple forum such as this. I suggest that you contact me off list ([email protected] is my e-mail address) and I will gladly load you up with all of the additional information mentioned above, which you can then digest at your leisure. After you’ve had an opportunity to study the new material on dwarf seahorses I provide, you will then be in a better position to revise your aquarium design, and I would be very happy to discuss your revised dwarf seahorse setup with you at that time.

You stated that you want your seahorses to have a very natural, safe aquarium, hero, but an aquarium with live corals would be neither natural nor safe for these pigmy ponies. In the wild, dwarf seahorses are found in shallow seagrass beds, not on coral reefs or patch reefs with live corals and gorgonians. So if you want to mimic their natural environment, I would recommend setting up a tank with lush beds of colorful macroalgae that will simulate their natural seagrass habitat. If hydroids appear in a dwarf seahorse tank that is heavily planted with macroalgae, the tank could simply be treated with fenbendazole to destroy the hydroids without harming the ponies or the beds of macroalgae, so it would be a natural, safe setup for your dwarf seahorses.

Also, I must advise you that you should plan to do without a Mandarin dragonet in your revised dwarf seahorse tank. The Mandarin would not molest the dwarf seahorses in any way, but it would be doomed to a slow death by starvation in any aquarium small enough to be suitable for dwarf seahorses.

Don’t get me wrong — I absolutely love the psychedelic coloration and peaceful nature of Mandarin dragonets! There’s no disputing that they are gorgeous little fishes and make ideal tankmates for seahorses in the right type of setup. They are docile, slow-moving, passive fish that are beautifully marked and very deliberate feeders. And they are quite hardy fish providing they can be fed properly. They have a heavy slime coat that seems to make them quite resistant to protozoan parasites such as Cryptocaryon irritans.

But, as you know, in order to do well, mandarins need a large, well-established aquarium loaded with live rock or live rock rubble that’s teeming with copepods and amphipods. Mandrins must have continuous opportunities to graze on suitable live foods or they generally slowly waste away and starve to death. In the right system, they can thrive, and will often learn to take small pieces of frozen Mysis, but they do best in well-established reef systems or aquariums with at least 1 pound of live rock or LR rubble per gallon, a mature sand bed, and a refugium that can continually replenish the pod population in the tank. Those are typically the conditions that are necessary to assure they have adequate suitable live prey.

Mandarins are bottom feeders that normally do not take food from the water column, so select an aquarium with a large foot print that can accommodate plenty of live sand, small pieces of live rock, live rock rubble, and macroalgae. If you want to maintain more than one Mandrin, and keep a male/female in top condition, the larger the aquarium (and therefore the more extensive pod hunting ground the Mandarins will enjoy) the better. Nowadays, no conscientious hobbyist would consider keeping a Mandarin dragonet in an aquarium smaller than 50 gallons, and most hobbyists would opt for a tank of 100 gallons or more for the sake of the Mandarins.

Please contact me off list, hero, and I will send you the additional information about dwarf seahorses for your ongoing research and you can proceed from there, armed with new information to guide you.

Best wishes with all your fishes, hero!

Respectfully,
Pete Giwojna

Dear hero:

Okay, now you’re talking! Overall, your new plan for keeping dwarf seahorses (Hippocampus zosterae) is vastly improved over your original concept and should be a workable design, and one that may produce very good results, at that.

I especially like your plans to vary the diet of the dwarf seahorses by offering a variety of copepods — that’s a very sound thinking that will pay off with improved vitality and increased breeding success. And it should also produce a better survival rate for the newborns.

The pre-cycled Macro Rocks are attractive and will provide your dwarf seahorse setup with all the benefits of live rock without the concomitant risk of introducing unwanted hitchhikers. Including lush beds of assorted macroalgae should do a nice job of simulating the natural seagrass habitat of H. zosterae, which the pint-size ponies are sure to appreciate.

However, I would suggest that you eliminate the Scarlet reef hermit crabs (Paguristes cadenati) from your dwarf seahorse tanks, just to be on the safe side — especially the smaller tank you will be using for the babies. If you’ll be using live Mysis in the dwarf seahorse tanks — which is an excellent idea and should be very successful — the adult mysids will do a fine job of scavenging in addition to producing larval Mysis for the seahorses to eat. They can take the place of the Scarlet reef hermits, which can just occasionally cause problems with the ponies when they are especially vulnerable, or with the snails in the cleanup crew.

The zoanthids you are considering have a number of good points which make them well-suited for more seahorse setups. For example, soft corals such as zoanthid polyps have very little stinging ability and generally make good choices for a modified reef tank that will include seahorses. Good choices include the zoanthid polyps (genus Zoanthus), which are tolerant of any light level and tolerate a wide range of water currents, meaning they will do well under the relatively low light and moderate water flow conditions that seahorses prefer. They grow very fast and are a great starter coral for beginners.

Equally desirable are the button polyps (genus Palythoa, etc.). They are extremely hardy and are an excellent starter coral. They prefer low to medium water flow, and will tolerate low light levels, making them another good choice for a seahorse setup. They come in a wide variety of colors and are readily available for a modest cost.

Clove Polyps Star Polyps or Daisy polyps (genus Clavularia) are another good choice. They are good starter corals that tolerate most any light level and do well under a variety of water currents. They are extremely hardy and relatively undemanding.

In short, zooanthids and polyps in general are seahorse-safe and your ponies won’t mind a tank housing several species of polyps. As far as their stings go, zoanthids and other polyps should be perfectly safe for your seahorses. But, as I am sure your already aware, you’ll want to observe a few precautions regarding the zoanthids before you consider adding them to a dwarf setup.

First of all, 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.

Secondly, "Zooanthus and Palythoa both contain very toxic chemicals, that can be dangerous to both reef inhabitants and humans. The most well known is Palytoxin, which has been documented as one of the most poisonous marine toxins known (Mereish et al, 1991). Palytoxin can affect the heart, muscles, and nerves leaving its victim in paralysis, and possibly death. Because of the toxin, you should never handle Zoanthus or Palythoa with open wounds, nor should you touch your mouth or eyes after handling the species. (We recommend the use of disposable latex gloves) When propagating either of the species, it is critical to remember that the slightest rub of an itchy eye, or even a small cut from a hang nail, might be enough to land you in the hospital. In the aquarium, some rapid growing Zoanthus colonies can be aggressive to stony and soft corals, but in general, they are very peaceful, and you can slow the growth rate by the controlling the overall nutrient load of your tank."

In general, aquarists need to handle any polyps from the genus Zoanthus and Palythoa with care, hero. If you do a Web search and Google "Zooanthus" and "Palythoa," you’ll find lots of photographs to go by regarding different species. It’s very difficult to be much more specific than that because the specimens are sold and marketed under so many different common names. For example, they might be called sea mats, button polyps, or colonial polyps, among many others.

Here’s what James Fatherree advises in that regard, hero:

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There are several types of commonly available zoanthids, including all of the palythoans, that can produce a deadly toxin (appropriately called "palytoxin"). It is found is the mucous coat that they cover themselves with, and if you get enough of it in an open wound, or your eye, mouth, etc. – it just might kill you. Many hobbyists have reported cases of numbness, sickness, and/or hallucinations, but the stuff is actually strong enough to kill, as well.

Handling them when you have a wound is an obvious no-no, but when you touch a colony and get the slime on your fingers (which is unavoidable with these things), it is imperative that you don’t rub your eyes, suck your fingers, or even pick your nose until you have washed your hands thoroughly. Really, you should never handle these without wearing protective gloves. Some hobbyists (including me) have handled zoanthids without gloves many, many times in the past, but it is now well-known that things can go very wrong when this is done, even if you have no wounds you know of and plan on washing your hands immediately after touching a specimen.

Wear the gloves! (James W. Fatherree, M.Sc., 2005)
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http://www.saltcorner.com/sections/guest/fatherree/Zoanthids.htm

So this is one of those cases when it’s better to be safe than sorry and err on the side of caution. When in doubt, don’t take chances — wear gloves and handle all colonial and button polyps with all due care. I would also wear gloves in any aquarium with bristleworms as a precaution — those spicules can be extremely irritating and bristleworms larger than 2-3 inches are capable of delivering a nasty bite.

Finally, hero, you need to be aware that zoanthids and polyps in general are susceptible to fenbendazole (Panacur). I think it is a wonderful idea — very important, in fact — for you to pretreat your tank with Panacur to prevent hydroids and Aiptasia rock anemones, and to maintain a very low dose of the Panacur in your dwarf seahorse tank thereafter to discourage the hydrozoans. But, if you want to give zoanthids a try in your dwarf seahorse tank, be sure to wait until the initial Panacur treatment has dissipated. If the zoanthids are going to survive in an aquarium that has been treated with Panacur, it will only be after the initial dose has been diluted to a very low level over time.

Best of luck with your dwarf seahorse setup, hero!

Respectfully,
Pete Giwojna

Dear hero:

I would consider mushroom corals for your dwarf seahorse setup. Mushroom corals, also called Corallimorphs or mushroom anemones, are very hardy corals. Among one of the best beginner corals, most mushroom coral prefer indirect light or shade rather than bright light and do best with low water movement, which means they will fit in well and prefer similar conditions to the dwarf seahorses. Mushroom corals come in many different colors like blue, red, green, brown, purple and often have stripes, spots, and mottled color variations. A very easy coral to keep, the mushroom coral prefers indirect light from fluorescents and low water current. They will often propagate until they completely cover the substrate upon which they grow. Mushrooms are generally not bothered by fenbendazole (brand name Panacur).

As for the zoanthids, hero, personally I would avoid them altogether in an aquarium that will be treated with Panacur. I would not want to take a chance with them because they are sensitive to fenbendazole and if they were to die, they could release harmful compounds into the aquarium that would be detrimental to the seahorses and other aquarium inhabitants. For me, it’s just not worth the risk…

But if you are determined to give zoanthids a try, suffice it to say that the longer you wait after you dose the tank with fenbendazole, the better. I would wait a period of months since the last dose of fenbendazole, but you will want to be maintaining a low level of fenbendazole in your dwarf tank continuously in order to prevent hydroids and Aiptasia rock anemones from appearing in the tank, and, under those circumstances, it would be best to skip the zoanthids to be on the safe side…

Best of luck with your dwarf seahorse corral, hero!

Respectfully,
Pete Giwojna

Dear hero:

You are very welcome to any and all of the information I can provide that will help to make sure your dwarf seahorse tank a success and ensure that your tour seahorses will thrive.

That is a good thought about using nudibranchs as a form of biological control to eliminate hydroids from your dwarf seahorse setup. There are indeed some nudibranchs that feed upon hydroids and other stinging organisms (cnidarians) such as anemones, and the nudibranchs in general would do just fine in a dwarf seahorse tank that provided them with suitable food.

So your premise is sound, hero: nudibranchs of all kinds will do well with seahorses, even the Pixies or dwarf seahorses (Hippocampus zosterae), providing you are able to provide the proper food for the particular nudibranchs you will be keeping. There will be no competition for food whatsoever between the dwarf seahorses, which need copious amounts of newly hatched brine shrimp (Artemia nauplii) and/or larval copepods for their daily diet, and the nudibranchs, which all have highly specialized diets. The nudibranchs would pose no threat whatsoever to the dwarf seahorses and vice versa.

However, it is very difficult to maintain most species of nudibranchs in the aquarium because it is typically all but impossible to provide them with a suitable diet. They are extremely specialized feeders, some of which feed only on certain types of stinging animals such as hydroids or anemones of a certain sort, and some of which feed only on other nudibranchs. The problem with using the nudibranchs to control the hydroids is that there are about a zillion different types of hydroids, and the diet of the nudibranchs is so specialized that they will often feed on only one genus or type of the hydroids. There is no way of knowing which of the many hydrozoans will appear in your dwarf seahorse tank, so it’s normally not possible to find the particular species of nudibranch that will eat the particular type of hydroids that are causing the problem in your aquarium.

Because it is so terribly difficult to meet the feeding requirements of most nudibranch species in captivity, very few types of nudibranchs are readily available to aquarists. In fact, there are only three different nudibranchs that you are likely ever to see offered for sale. They are the Berghia nudibranchs, which eat Aiptasia rock anemones, the lettuce nudibranch (Elysia crispata), which eats certain types of macroalgae, and the blue velvet sea slug, which eats certain types of flatworms. Unfortunately, none of the nudibranchs that are readily available in the aquarium hobby are predators of hydroids.

You might consider keeping Berghia nudibranchs in your dwarf seahorse tank to eliminate Aiptasia rock anemones. The Berghia nudibranchs are easy to obtain and they would keep your dwarf seahorse setup free of the Aiptasia rock anemones or glass anemones, hero. (You can obtain Berghia nudibranchs bred and raised for controlling Aiptasia at the following website:http://www.berghia.net/aiptasiacontrol.html) But you would still want to does your dwarf seahorse tank with fenbendazole (brand name Panacur) to prevent hydroids from becoming established in your dwarf tank, and I suspect the fenbendazole would be very detrimental to nudibranchs of any kind. The nudibranchs are essentially shell-less marine snails, and the fenbendazole is harmful to several types of snails.

Likewise, if you’re going to go with a five-gallon dwarf seahorse setup with lush beds of macroalgae, there is one species of nudibranch that would do very well with dwarf seahorses in a heavily planted aquarium. It is commonly known as the Lettuce Nudibranch.

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

The Lettuce Nudibranch feeds on certain types of Caulerpa and Bryopsis algae in a rather unusual manner. They don’t graze on the macroalgae like a snail as you might expect. Rather, they essentially suck the chloroplasts from certain Caulerpa and incorporate those chloroplasts into their own living tissue in a process known as kleptoplasty. The chloroplasts they have hijacked in this manner will then continue to produce food for the nudibranch via photosynthesis if the aquarium receives enough light. So as long as the aquarium is lighted and contains a thriving colony of Caulerpa macroalgae, the Lettuce Nudibranch will often do very well.

Again, however, hero, you would want to maintain a very low level of fenbendazole in your dwarf seahorse setup with the lush beds of macroalgae, and that could be deadly for the lettuce nudibranch as well. I have never attempted to keep nudibranchs in a tank with Panacur, so I cannot say for sure whether any particular nudibranchs are sensitive to the medication, but I strongly suspect that they would be…

Otherwise, hero, I think it is a splendid idea to set up a five-gallon dwarf seahorse tank with lots of macroalgae and then to set up a separate nano reef tank that can house zoanthids and other live corals.

Here’s hoping that you come up the perfect dwarf seahorse setup for your needs and interests and the perfect way to keep it free of hydroids!

Respectfully,
Pete Giwojna

Dear hero:

Yes, sir, you are quite correct — the section of the article that you quoted was discussing compatible tankmates for dwarf seahorses (Hippocampus zosterae) and I did indeed list the Feather Dusters as suitable companions for the pint-size pigmy ponies. They Feather Dusters are fancy filter feeders that would do well under the same conditions that are suitable for dwarf seahorses.

You are equally astute in deducing that the Feather Dusters or tubeworms would not survive in a tank that was dosed with fenbendazole (brand name Panacur). The fenbendazole is an anthelmintic or deworming agent used on large animals such as horses at it is death to worms of all kinds, including the feather duster tubeworms.

Dwarf seahorse keepers must therefore choose between keeping Feather Dusters in the tank with their miniature marvels or dosing the tank with fenbendazole to prevent hydroids and Aiptasia rock anemones from gaining a foothold. In my experience, that’s a no-brainer — I would exercise the Panacur option to protect my dwarf ponies from stinging animals such as hydroids and anemones and do without the live corals and feather dusters and other organisms that are sensitive to the medication.

Best of luck with your ongoing research, hero! Keep reasoning things out, sir — you’re doing fine and you will eventually work out the type of dwarf seahorse tank that’s best suited for your needs and interests.

Respectfully,
Pete Giwojna

Dear hero:

Yes, sir, I agree — whenever possible, I recommend raising the newborn dwarf seahorses in a nursery tank of their own separate from the adults.

It’s true that newborn dwarf seahorses eat the same food as the adults and can be raised right alongside their parents in the same aquarium if need be, but for best results, you need to alter your feeding regimen and maintenance schedule somewhat when you are raising the fry. For example, the adults do well with two feedings a day, but the babies require more frequent feeding and will do better if they are fed 3-5 times a day. Ideally, newly-hatched brawling shrimp should be available to the young at all times so they can feed at their leisure throughout the day. And when you are feeding more often, you will also need to perform more frequent water changes and siphon fecal pellets up regularly in order to maintain water quality, as discussed below.

Cannibalism is unknown in H. zosterae, and one of the neat things about them is that the fry can often be reared in the main tank right alongside their parents since the newborns eat the same foods as the adults. However, to maximize growth and improve survivorship, 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 air-operated undergravel or sponge filters works great for this and can be set up in much the same way as the adult tanks. A 1-gallon or 2-gallon goldfish bowl equipped with an undergravel filter and suitable hitching posts makes a fine nursery tank for dwarf seahorses, but of the options you mentioned in your post, hero, I like the 4-gallon aquarium with the built-in undergravel filters the best. However, as you know, the larger water volume in the four-gallon setup would make it more difficult to maintain an adequate feeding density for the newborns. One way around that problem would be to keep the four-gallon aquarium only half-full of saltwater, so that so that it only holds 2 gallons of water. The undergravel filters will still work just as well but the smaller water volume would make it easier to maintain a good feeding density for the young.

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 for benthic seahorse fry. 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.

In this type of simple nursery setup, you stay on top of water quality by making small partial water changes a few times every day while using a length of airline tubing to siphon fecal pellets and dead or uneaten rite shrimp from the bottom of the tank. Nurseries for benthic fry such as dwarf seahorses don’t need to be fancy at all. (Heck, back in the day, my nursery tank for my first dwarf seahorses was an empty mayonnaise jar and even that did the trick as long as I performed partial water changes very regularly in conjunction with siphoning the bottom clean.)

As always, 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 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.

Remember that a brood of baby seahorses generates a tremendous amount of waste. Like all babies, seahorse fry exist only to eat and poop. To say they are voracious is a gross understatement — at this stage of their development, the newborns have but one mission in life: to eat and thus to grow. Researchers have found that a single seahorse only a few weeks old can consume 3000-4000 newly hatched brine shrimp in a single day! Milligram for milligram, a great white sharks feeding habits appear downright dainty and positively anorexic compared to a baby seahorse on the prowl for live prey. And as you can imagine, when well-fed fry eat that much, defecation is amazingly rapid, with each newborn producing an average of one fecal pellet every 25-30 minutes. Multiply that by several dozen fry and you can see that it doesn’t take very long for the bottom of your nursery tank to become carpeted with fecal pellets.

Since the nursery tanks have limited filtration, daily water changes are the only way to keep up with the metabolic wastes and oxygen demand of several dozen baby seahorses and the thousands of brine shrimp needed to feed them. The best way to perform the necessary maintenance is to use a length of airline tubing to siphon off the waste that accumulates on the bottom at least twice a day (noon and evening are ideal for this). Replace the water that was removed while siphoning with freshly mixed saltwater that has been pre-adjusted to the same temp and salinity as the nursery tank. Change about 10% of the water each time you siphon the bottom, so that a total of at least 20% of the water in the nursery tanks is exchanged every day.

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). Those figures certainly can be improved, but realistically, in order to increase survivorship much higher you must consider other food sources for the fry and be willing to explore more sophisticated nursery tanks.

Marine copepods are the ideal food for dwarf seahorse fry. Field studies have shown that copepods comprise the bulk of the diet of Hippocampus zosterae in the wild (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). Other research projects have shown conclusively that seahorse fry feed on larval copepods grow markedly faster and show increased survivorship that fry raised on newly hatched Artemia (Payne, M.F. and Rippingale, R.F. Rearing West Australian seahorse, Hippocampus subelongatus, juveniles on copepod nauplii and enriched Artemia. Aquaculture 188_2000.353-361). Copepods are natural food source for seahorses in the wild and they are adapted to feeding on them. As a result, they digest copepods much more efficiently and completely than brine shrimp, which is an unnatural food for them that does not exist in the ocean.

If you wanted to try a more sophisticated nursery setup in anticipation of regular broods of dwarf babies, hero, then I would suggest setting up a five-gallon or 10-gallon aquarium as a divided nursery for your dwarf fry. The basic Divided Nursery tank design, which simply involves separating a standard five-gallon or 10-gallon aquarium into two or more different compartments with a common water supply using perforated tank dividers. All of the equipment and filtration goes into one of the resulting compartments while the other compartment(s) serve as the nursery or nurseries for the fry.

The perforated barrier allows water to circulate freely between the compartments while acting as a baffle that greatly dampens the turbulence generated on the equipment side.

It is also very effective at keeping newly hatched brine shrimp confined to the fry’s nursery compartment, especially if two or three of the perforated plastic dividers are sandwiched together side-by-side with a small 1/8-1/4-inch gap between them, forming a double barrier (Abbott, 2003). In your case, hero, I would go one step further and cover the perforated tank dividers with plastic window screen or better yet the plastic mesh sold in craft stores for needlepoint projects to increase the effectiveness of the barriers (Abbott, 2003). Then I would darken the equipment side and position a strip reflector or table lamp at the end of the nursery compartment opposite the filtration side, in order to draw the baby brine shrimp (bbs) away from the tank divider and filters, while concentrating the bbs in a smaller area so the fry can feed more efficiently (Abbott, 2003).

All of the gear is thus isolated on one side of the partition safely away from the fry and their food. In the nursery setup, the bulk of the tank is reserved for the filtration equipment, with the smaller compartment housing the newborn dwarf seahorses and their live food (Artemia nauplii and/or larval copepods). The larger volume of water a divided tank provides gives the nursery greater stability as far as fluctuations in temperature and pH go, makes it easier to maintain optimum water quality, and increases your margin for error accordingly (Abbott, 2003). With the tank divided in this way, any sort of mechanical, chemical or biological filtration you care to provide can be safely operated in the equipment area without disturbing the delicate fry in the nursery area (Abbott, 2003). The developing young thus enjoy all the benefits that better filtration and a large water volume can provide, while being confined in a smaller nursery compartment, making it easy to maintain an adequate feeding density (Abbott, 2003).

To provide efficient biofiltration for the divided nursery, hero, I would install a fluidized sand filter on the equipment side. Fluidized bed filters use a fine sand media suspended in upflowing water currents that provides a tremendous amount of surface area for beneficial bacteria to grow, and allows the filter to nitrify large amounts of ammonia while maintaining high overall water quality and stability. There would be no ammonia spikes with such a nursery.

Further details on breeding and rearing your Pixies are available in Alisa Abbott’s guidebook titled Complete Guide to Dwarf Seahorses in the Aquarium. 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!

When it comes to the main tank for the adult dwarf seahorses, hero, there are all sorts of options that you can consider, as we have already discussed off list as well as in previous posts. Here are some posts from other dwarf seahorse keepers explaining the type of tanks they prefer and how they modified the filters for those aquariums to make them suitable for their pint-size pygmy ponies:

> I’m having a hard time keeping my dwarfs from getting stuck to my
> recirculating pump supply opening in the back wall of my nano….Any ideas
> how to fix this problem?
>

Simplest method:
Hang a rectangular sponge suspended on strings over the edge of the
tank… let sponge be sucked against the intake.

Engineered method:
Silicone a plastic cover over the intake slots. This plastic cover
will need a hole drilled in it just big enough to retrofit part of the
elbow of an AZOO bio Sponge filter to it. The sponge will keep the
horselets and brinies from being run through the filter.

Ken McGuire’s Dwarf Pico Tank

In a message dated 7/9/2008 11:42:58 A.M. Central Daylight Time, [email protected] writes:
You might consider a 3 gallon Pico Tope at Drs Foster and Smith. It
comes with a good filter. An Azoo Bio Sponge fits the intake tube
perfectly. You will need to modify the sponge so it will fit
between the tube and the glass. Some brineys still get in the
sponge, but it is cuts way down on the briney loss due to
filtration, and the filter is just the right size for a 3 gallon to
keep the shrimp moving but slow enough so the seahorses can feed.

I wouldnt have any other set up for dwarves now.
I tried a 10, and a 2.5 gallon set up. The 3 Gallon seems to be the
easiest to use for small herds of a dozen or less. I recommend only
6 or 12 dwarfs for a 3 gallon. They display well in this tank.
Easy Filtration System for Dwarf Seahorses

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

See my design here:

<http://us.share.geocities.com/ken_mcguire/Filter.bmp&gt;

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

Ken.

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

Hi Ricky,

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

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

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

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

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

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

Happy to help with any other questions.
Susan

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

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

"D’s" Tips for Raising Dwarf Seahorses

Ricky,

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

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

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

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

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

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

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

"D"

That’s the current thinking on modified aquariums for dwarf seahorses, hero. Some hobbyists also report good success using the Biorb aquarium system systems for dwarf seahorses. The built-in filtration system in the biOrbs functions primarily as an undergravel filter, supplemented with mechanical and chemical filtration cartridges, and I have often Dwarf seahorses successfully with undergravels.

My only concern about the Biorb is the light fixture. The halogen bulb may give off a significant amount of heat, and with the top of the tank capped off like that, it’s possible that the light might raise the aquarium temperature to undesirable levels after it’s been running all day. I’ve had no experience with the Biorb so I don’t know if that’s the case or not, but the possibility does concern me. However, the top includes air vents and a heat exchange system to help cool the tank, so that may effectively prevent overheating. And, of course, even the heat given off from the lamp should prove to be a problem, it could be easily solved by removing the light fixture/top and allowing the ambient room light or a nearby table lamp to provide the illumination.

At any rate, it certainly looks like it would work well and I wouldn’t hesitate to give it a try. A whole range of accessories are available for the tanks and they are the right size to accommodate the whole herd of dwarf seahorses. Yet they are not so large so large that it would be overly difficult to maintain an adequate feeding density of baby brine shrimp.

Okay, hero, those are some other ideas you might want to keep in mind when you are planning your dwarf seahorse set up and deciding what type of filter to go with the larger tank, and how to modify it to make it safe for the dwarfs.

Best wishes with all your fishes!

Respectfully,
Pete Giwojna