Seahorse Breathing Question

Dear Grant:

Your spiny seahorse is probably Hippocampus barbouri, a species which is commonly known as the prickly or spiny seahorse, zebra-snout seahorse, or simply as "barbs," for short. All seahorse keepers are familiar with these thorny beauties. They are the pretty, prickly, tropical seahorses we all used to know and love as Hippocampus histrix until the histrix complex was revised and taxonomists officially changed their name to H. barbouri (Abbott, 2003). They are readily identified by their sharp, very well developed spines, their prominent five-pointed crown, and their boldly striped snouts (Abbott, 2003). The latter is one of their most attractive features and is responsible for one of their common names — the zebra-snout seahorse. Cultured specimens range from pale yellow to a brilliant red-orange, often further adorned with reddish brown spots and lines.

There is no easy answer to your question regarding the normal breathing rate of seahorses, Grant. Their respiration rate varies according to the levels of oxygen and carbon dioxide in the aquarium, the water temperature, their metabolic rate, their activity level, and their emotional state.

Unlike human beings, which are homeothermic and maintain homeostasis at all times, seahorses are of course cold-blooded creatures, so their metabolic rate is determined largely by the water temperature. The warmer the water temperature, the higher their metabolism and the greater their oxygen demand becomes, and their breathing rate goes up according. At lower water temperatures, the seahorse’s metabolism and oxygen demand are reduced, and their breathing rate slows.

The level of oxygen in the atmosphere that we breathe is quite stable and constant, but that’s not the case with the level of oxygen in an aquarium. For example, the warmer the aquarium water is, the less dissolved oxygen it can hold, and the higher the salinity of the aquarium water, the less dissolved oxygen it can hold. So the amount of oxygen in the water varies with the aquarium temperature and specific gravity.

Likewise, the levels of oxygen and carbon dioxide in an aquarium varies from day to night due to the photosynthesis performed by macroalgae and zooanthellae. When the aquarium reflector is on, providing plenty of light, the algae and plants in the aquarium take in carbon dioxide and release oxygen as a byproduct of photosynthesis. As a result, the pH of the water and the dissolved oxygen levels rise throughout the day, while the level of dissolved carbon dioxide drops.

On the other hand, during the night when the aquarium light is turned off and no photosynthesis takes place, the plants will begin to take in oxygen and give off carbon dioxide. This has exactly the opposite effect — the pH of the aquarium water and the level of dissolved oxygen drop at night, while the amount of dissolved carbon dioxide rises. This can occasionally become a problem in a small, poorly circulated, closed-system aquarium that is very heavily planted if the oxygen levels drop so much during the night and the carbon dioxide levels rise so high that the seahorses have difficulty breathing and getting enough oxygen.

So in an aquarium where they dissolved oxygen levels are low and/or the carbon dioxide levels are high, seahorses will exhibit very rapid respiration. They will often be pale in coloration and perch near the surface of the aquarium, often with their heads directly in the outflow from the filter, where the oxygen levels are highest.

Seahorse setups are often more susceptible to such problems because hobbyists are so conscious of their seahorses’ limited swimming ability that they tend to leave their aquariums undercirculated. Poor circulation and inadequate surface agitation can lead to inefficient oxygenation and insufficient offgassing of carbon dioxide, aggravating the situation.

Seahorses are more vulnerable to the low O2/high CO2 levels 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.

Warm water temperatures exacerbate such problems in the aquarium. 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 double whammy creates a dangerous situation for seahorses and may well result in respiratory distress and rapid, labored breathing.

For best results with your seahorses, Grant, strive to maintain stable water conditions in your Biocube within the following aquarium parameters at all times:

Temperature = optimum 72°F-75°F (22°C-24°C).
Specific Gravity = range 1.022 – 1.026, optimum 1.0245
pH = 8.2 – 8.4
Ammonia = 0
Nitrite = 0
Nitrate = 0-20 ppm; optimum 0-10 ppm

Provide good surface agitation and aeration in order to promote better oxygenation and facilitate better gas exchange at the air/water interface.

Your seahorses’ respiration rate may increase naturally when they are feeding, actively courting, being handled, or excited in general, and then return to their normal resting respiratory rate afterwards, Grant. That’s natural and nothing to be concerned about. Symptoms of respiratory distress are ordinarily pretty obvious and you should have no trouble determining when your seahorse is laboring or struggling to breathe.

For example, seahorses that are stressed or suffering from gill disease or parasites that attack the gills will exhibit rapid respiration, labored breathing, huffing, panting, yawning or coughing behavior, and other indications of respiratory distress. So familiarize yourself with your seahorse’s normal respiration rate when they are comfortable and healthy, which will vary somewhat with water temperature and their activity level or degree of arousal/excitement as we have been discussing, and any subsequent changes in their normal breathing pattern can alert you to a possible problem.

Ocean Rider markets a strain of captive-bred-and-raised Hippocampus barbouri under the trade name of Spikeys, Grant, but they are currently out of stock. You might try Oceans, Reefs and Aquariums (ORA) to see if they have a male zebra-snout seahorse (H. barbouri) available, sir. Otherwise, keep a close eye out wherever you obtained the female to see if a male may become available through them.

Best of luck with your spiny seahorse, Grant!

Respectfully,
Pete Giwojna

Dear Grant:

You’re very welcome, sir!

Here are John’s instructions explaining how to post a picture on this forum:

<Open quote>
1st you have to host it somewhere like photobucket or in my case AOLmyspace
but you must make it small as the board will only take a small photo.

You click on the orange Img tag in the reply window and add your address of the hosted PIC etc.. Wherever.com newseahorse.jpg

Make sure to hit the close all tags tab after you are finished and then preview your post to see if it worked that way you can keep trying till you get it right without posting.

An image resize tool is very helpful.

For a larger image you could add a link with URL tab to the hosted photo. In some cases it will not work for all people but will for others it will (I never understood that) prob an AOL issue in my case!

HTH,

John
<end quote>

Best of luck with your new seahorse, Grant! If your spiny seahorse is indeed Hippocampus barbouri, it should be evident from the photographs. Try to include a picture that shows the crownlike coronet on the top of the seahorse’s head clearly.

Happy Trails!
Pete Giwojna

Dear Grant:

That’s a very pretty pony and the fancy fronds that adorn its head and back really give it a fancy appearance.

Those hair-like tentacles on the head and neck are known as dermal cirri, and are an attractive adornment possessed by certain seahorses. Dermal cirri are fleshy tabs or branching outgrowths of the skin that serve to break up the seahorse’s outline and allow it blend into its weedy habitat all the better, a sort of natural camouflage. Unlike spines, cirri are not permanent structures in most cases. Up to a certain age at least, seahorses appear to be capable of growing or shedding these fleshy filaments as the occasion demands in order to better suit their surroundings. For example, specimens that are rafting in clumps of Sargassum are apt to have well-developed cirri, giving them an appropriately shaggy appearance, while a seahorse inhabiting the mudflats of an estuary will be smooth skinned. Cirri grow most commonly on the head and neck region and are more common in juveniles than adults.

The presence of cirri is a highly variable trait and some species never have them. They are very rare or nonexistent in many seahorses, while in other species they are relatively common. For example, Hippocampus comes and H. reidi are smooth-bodied seahorses that never seem to develop cirri (Giwojna, Oct. 2003). Consider them cue balls — the Kojaks of seahorses. On the other hand, Hippocampus guttulatus are famous for their cirri and many Pot-Bellies (H. abdominalis/H. bleekeri) also sport fancy headdresses (Giwojna, Oct. 2003).

But even in seahorses where cirri are not uncommon, such as Hippocampus zosterae and H. erectus, the occurrence of cirri varies greatly from individual to individual (Giwojna, Oct. 2003). Most dwarf seahorses have no cirri, but some of them are regular little fuzz balls. That’s the case with Hippocampus erectus as well. Most Lined Seahorses (H. erectus) lack these appendages altogether, some have just a few, and the individuals with really extravagant cirri are relatively rare (Giwojna, Oct. 2003).

It’s a shame seahorses with well-developed cirri aren’t more commonplace because they can be quite breathtaking. A heavy growth of cirri can transform an ordinary specimen into a real show horse, making them appear as if they were adorned with a fancy mane or wearing an Indian war bonnet. A seahorse with extravagant, well-developed cirri can indeed be very exotic looking, but sometimes it has the opposite effect, lending them a comical appearance instead (Giwojna, Oct. 2003). I’ve seen shaggy specimens that looked like they were having a bad hair day, sporting a Mohawk or spike hairdo (Giwojna, Oct. 2003). Voila — a punk-rock pony, going through its rebellious teenage phase! Either way, they dress up the seahorses and give them a little extra pizzazz, and that’s what makes seahorse keeping so much fun!

Unfortunately, in this case, the heavy growth of cirri on the head of your seahorse obscures the coronet and make it difficult to identify with any certainty. I agree that it does not appear to be Hippocampus barbouri — the snout is not striped and it lacks the sharp spines that are so characteristic of this species. Neither is it H. reidi, H. kuda, H. comes, H. ingens or H. kelloggi.

The seahorse has the robust, deep-chested body of Hippocampus erectus, and erectus is one of the species that sometimes developed extravagant cirri, but it lacks the lined coloration pattern that is so characteristic of H. erectus. It’s not uncommon for the lined pattern to be obscured or difficult to detect on some specimens of H. erectus, though, so we can’t rule out that identification.

I might be inclined to think it was a specimen of H. guttulatus, which are so well known for their beautiful cirri, but we never see that species on this side of the pond.

I’m sorry to say that I can’t identify the seahorse from your picture with any degree of certainty. I believe the dealer you got the seahorse from called it a "spiny seahorse" because of its well-developed cirri, and not because of its spiny exoskeleton, which is why common names are very often misleading and useless for purposes of identification.

In any case, it’s a very beautiful seahorse and I would suggest trying to obtain another specimen of the same kind from the same source where you got this pony.

Best of luck with your new seahorse, Grant!

Respectfully,
Pete Giwojna

Dear Grant:

The presence of cirri is certainly not a dominant trait in most seahorse species, but I don’t know if it conforms to the classic laws of Mendelian genetics and is a simple recessive trait that can be inherited from the parents if both of them carry the gene and pass it on, or not, sir. But I suspect it is quite a bit more complicated than that.

For example, the development of cirri often seems to have more to do with the environment than with genetics. Many researchers assume that the cirri are simply epidermal projections that grow in response to external stimuli for the purpose of camouflage (Todd Gardner, pers. com.). Some of the habitat features that are believed to promote the growth of cirri are a weedy environment and fast water flow. I suspect that in order to develop cirri a seahorse must have both a genetic predisposition for the trait and the right environment to stimulate the development of the dermal appendages.

Lucy Woodall has been researching the population genetics of H. guttulatus and H. hippocampus, and has observed elaborate cirri in both species, but thus far has not found any genetic correlation for the trait. However, it is interesting to note that the branching of the cirri is different in specimens of H. guttulatus as opposed to specimens of H. hippocampus (Woodall, pers. com.).

Further confounding the matter is the fact that cirri are often a transitory trait. Most seahorses that possess them lose the cirri over a period of weeks or months as they grow. Cirri are thus seen much more often on juvenile seahorses and are fairly rare on adult seahorses of the species.

Be that as it may, I can assure you that shaggy seahorses with the elaborate cirri will mate readily with seahorses of the same species that lack cirri altogether, and vice versa. So you don’t necessarily need to find another shaggy seahorse to pair with your female, Grant.

In home hobby tanks, where different species of seahorses are often mixed freely, crossbreeding or interspecific hybridization does occasionally occur, but it is quite uncommon, especially when seahorses have potential partners of their own species available to them. The prolonged, elaborate courtship ritual that seahorses go through before mating occurs generally prevents seahorses from different species from breeding successfully. Suffice it to say that seahorses are much, much better at species recognition than we are, and that given a choice, they almost always prefer to mate with their own kind. Almost always.

However, the urge to reproduce is very strong in seahorses. For example, solitary males often go through the motions of courtship when there are no other seahorses present in their aquarium. They may court their own reflection and sometimes even direct their courtship displays toward their keepers. Dwarf seahorse stallions in particular are irrepressible in that regard, and a hitching post may suffice for them as a surrogate, when no better alternative is available! Homosexual mating attempts (both male and female) are also common when no member of the opposite sex is present. (Fielder reported a case where two male Hippocampus hippocampus courted one another for over two hours and unsuccessfully attempted at least 20 copulatory rises together.)

Now, where a male and female seahorse of different species are confined together, they most often simply ignore one other when it comes to breeding. But other times the instinct to breed overwhelms any interspecific inhibitions, and with no other available partner, the male will attempt to flirt with the female regardless of their differences. Results vary when this occurs, but the resulting offspring are generally perfectly viable.

In your case, Grant, I would suggest pairing your seahorse with an H. erectus stallion. The body build and profile of your seahorse most closely resembles H. erectus, and that is a species that occasionally develops extravagant cirri. It’s possible that your female may be H. erectus or that, if she is not, she may accept an erectus stallion as a mate.

At this point, I would also like to say that you have a very attractive mini reef flourishing in your Biocube. That’s a very colorful, natural setting for your seahorse and she certainly appears to be happy in her little patch of Paradise.

However, when keeping seahorses in an appropriately elaborate environment such as your nano reef, it is imperative that you feed them properly! Domesticated seahorses thrive on enriched frozen Mysis as their staple, everyday diet. But the worst thing you can do when feeding the seahorses in a intricate reef or live rock environment is to scatter a handful of frozen Mysis throughout the tank to be dispersed by the currents and hope that the hungry horses can track it all down. Inevitably some of the frozen food will be swept away and lodge in isolated nooks and crannies where the seahorses cannot get it (Giwojna, 2005). There it will begin to decompose and degrade the water quality, which is why ammonia spikes are common after a heavy feeding. Or it may be wafted out into the open again later on and eaten after it has begun to spoil. Either outcome can have dire consequences (Giwojna, 2005).

The best way to avoid such problems is to target feed your seahorses or set up a feeding station for them. See my online article in Conscientious Aquarist for a detailed discussion explaining exactly how to set up a feeding station and train your seahorses to use it:

Click here: Seahorse Feeders
http://www.wetwebmedia.com/ca/volume_2/cav2i5/seahorse_feeders/seahorse_feeders.htm

Personally, I prefer to target feed my seahorses instead. The individual personalities of seahorses naturally extend to their feeding habits. Some are aggressive feeders that will boldly snatch food from your fingers, while some are shy and secretive, feeding only when they think they’re not being observed. Some like to slurp up Mysis while it’s swirling through the water column, and some will only take Mysis off the bottom of the tank. Some are voracious pigs that greedily scarf up everything in sight, and some are slow, deliberate feeders that painstakingly examine every morsel of Mysis before they accept or reject it. Some eat like horses and some eat like birds. So how does the seahorse keeper make sure all his charges are getting enough to eat at mealtime? How does the hobbyist keep the aggressive eaters from gobbling up all the mouth-watering Mysis before the slower feeders get their fair share? And how can you keep active fishes and inverts with seahorses without the faster fishes gobbling up all the goodies before the slowpoke seahorses can grab a mouthful (Giwojna, unpublished)?

Target feeding is the answer. Target feeding just means offering a single piece of Mysis to one particular seahorse, and then watching to see whether or not the ‘horse you targeted actually eats the shrimp. Feeding each of your seahorses in turn that way makes it easy to keep track of exactly how much each of your specimens is eating (Giwojna, unpublished).

There are many different ways to target feed seahorses. Most methods involve using a long utensil of some sort to wave the Mysis temptingly in front of the chosen seahorse; once you’re sure this has attracted his interest, the Mysis is released so it drifts down enticingly right before the seahorse’s snout. Most of the time, the seahorse will snatch it up as it drifts by or snap it up as soon as it hits the bottom (Giwojna, unpublished).

A great number of utensils work well for target feeding. I’ve seen hobbyists use everything from chopsticks to extra long tweezers and hemostats or forceps to homemade pipettes fashioned from a length of rigid plastic tubing. As for myself, I prefer handfeeding when I target feed a particular seahorse (Giwojna, unpublished).

But no doubt the all-time favorite implement for target feeding seahorses is the old-fashioned turkey baster. The old-fashioned ones with the glass barrels work best because the seahorses can see the Mysis inside the baster all the way as it moves down the barrel and out the tip. By exerting just the right amount of pressure on the bulb, great precision is possible when target feeding with a turkey baster. By squeezing and releasing the bulb ever so slightly, a skillful target feeder can keep a piece of Mysis dancing at the very tip of the baster indefinitely, and hold the tempting morsel right in front of the seahorse’s mouth as long as necessary. Or if the seahorse rejects the Mysis the first time it drifts by, a baster makes it easy to deftly suck up the shrimp from the bottom so it can be offered to the target again. In the same way, the baster makes it a simple matter to clean any remaining leftovers after a feeding session (Giwojna, unpublished). (You’ll quickly discover the feeding tube is also indispensable for tapping away pesky fish and invertebrates that threaten to steal the tempting tidbit before an indecisive seahorse can snatch it up.)

In short, target feeding allows the hobbyist to assure that each of his seahorses gets enough to eat without overfeeding or underfeeding the tank. And it makes it possible to keep seahorses in a community tank with more active fishes that would ordinarily out-compete them for food, since the aquarist can personally deliver each mouthful to the seahorses while keeping more aggressive specimens at bay (Giwojna, unpublished).

The key to keeping active specimens like firefish and occelaris clownfish or cleaner shrimp successfully with seahorses is to feed the other fish and inverts with standard, off-the-shelf aquarium foods first, and once they’ve had their fill, then target feed the seahorses (Giwojna, unpublished).

Best of luck finding a mate for your female, Grant!

Respectfully,
Pete Giwojna

Dear Grant:

It’s good to hear that your new female is making the transition to frozen foods so well.

Can you refresh my memory regarding the size of your Biocube, sir? Is your setup a 12-gallon nano tank, a 24-gallon Biocube, or what? I need to know how big your Biocube is in order to give you a good answer regarding the proper stocking density for the tank.

But offhand I would say that adding any more than one new seahorse would probably be pushing things, considering the amount of invertebrates that are already in the tank.

Yes, sir, you are quite correct in assuming that seahorses will breed more readily in a small, closed-system aquarium than clownfish or angelfish will. However, reproductive success with seahorses often depends largely on whether they are wild-caught specimens or cultured seahorses. Allow me to elaborate.

Environmental triggers, such as changes in salinity, and other seasonal changes often have a strong influence on breeding in the aquarium, particularly for wild seahorses. Wild-caught seahorses may have a difficult time adjusting to captive conditions, don’t tolerate crowding at all, and most importantly of all, in the aquarium they lack the type of seasonal or cyclical environmental cues (falling water temperature, changes in day length, reduced salinity from monsoon rains, moon phases and high tides, etc.) they normally experience in the wild that regulate the breeding season. These environmental stimuli trigger the secretion of gonadotropin and other key hormones that prepare them for breeding and govern their reproductive activity. Without these environmental cues and the hormonally induced changes they trigger, many times wild-caught seahorses simply do not breed in captivity. (For instance, studies by fish endocrinologists show that it takes at least two years for wild fish just to adjust to a reverse photoperiod in the aquarium if they are from the southern seas and are now being kept in the northern hemisphere.)

The point is that breeding may not occur without the proper environmental stimuli to trigger the secretion of pituitary hormones. This often presents a problem in the aquarium, especially for wild-caught seahorses. Artificial lighting eliminates daylight as a cue, heaters prevent temperature fluctuations, and hobbyists take pains to keep the salinity rock solid. Such stability in aquarium conditions is generally a good thing — the goal that all conscientious aquarists are taught to strive for, but it is not necessarily the best thing to promote breeding (Indiviglio, 2002). With no seasonal changes in day length, water temperature, or salinity to trigger a surge in gonadotropin and get the ball rolling, reproductive activity in wild-caught seahorses can grind to halt. This problem was often exasperated in the past by the fact that hobbyists often kept wild ponies in aquariums that were too shallow for them to mate successfully.

In short, breeding in Hippocampus is often seasonal, regulated by cyclical changes in water temperature, day length, and salinity (monsoons). In the wild, both temperate and tropical seahorses breed best during the summer months and typically take a break from breeding during the offseason. Although domesticated seahorses that have been born and bred for aquarium life for generation after generation are no longer as strongly dependent on such environmental cues and will often breed year-round in captivity, even captive-bred seahorses sometimes experience a lull in the festivities at this time of year. That’s just their natural breeding cycle, the rhythm of life built into their genes.

Breeding is another area where wild seahorses simply cannot compete with their captive-bred counterparts. In the olden days, greater seahorses removed from the wild rarely bred in captivity. There were a number of reasons for this ranging from traumatic capture techniques and mishandling by dealers to difficulty adjusting to a captive environment to the sort of feeding problems we’ve been discussing above. But one big factor was that in the aquarium they lacked the type of seasonal or cyclical environmental cues (falling water temperature, changes in day length, reduced salinity from monsoon rains, moon phases and high tides, etc.) they normally experience in the wild that regulate the breeding season. These environmental stimuli trigger the secretion of gonadotropin and other key hormones that prepare them for breeding and govern their reproductive activity. Without these environmental cues and the hormonally induced changes they trigger, many times they simply ceased to breed in captivity. Researchers dealt with such setbacks through wild procurement of gravid males. In other words, loaded or pregnant males removed from the wild provided the fry needed for rearing projects and laboratory study in those days. Those were truly the Dark Ages of seahorse keeping.

Nowadays, captive-bred seahorses normally experience no such difficulties in the boudoir. They are highly domesticated and very well adapted to the aquarium environment. Unlike wild seahorses, they are not subject to traumatic capture methods or mishandling and abuse en route to the hobbyist. Born and bred for captivity generation after generation, for them the aquarium is their natural habitat. As a result, for the most part, they have lost their dependence on seasonal cues and external stimuli when it comes to mating. Rather than external environmental cues, for farm-raised seahorses, which have been raised at far greater population densities than seahorses ever experience in the wild, it is the presence of other seahorses — potential mates — that appears to get their hormones flowing and triggers courtship. (Pheromones or sex hormones almost certainly play a role in this.) In other words, living amidst a group of potential partners at all times seems to be what turns on captive-bred seahorses, and breeding appears to be their number one mission in life. Compared to their wild conspecifics, farm-raised seahorses seem to court constantly, breed like bunnies, and change partners often.

In fact,nowadays, the primary concern of many new seahorse keepers who are not prepared for rearing the young is how to prevent their prolific CB ponies from settling down and breeding. Some aquarists will keep their seahorses in a unisex environment in order to avoid breeding so they don’t have to deal with brood after brood of young.

If you have a compatible pair of captive bred and raised seahorses and you provide them with optimum water quality, good nutrition, and the stress-free environment, the chances are excellent that they will produce offspring at some point, Grant.

No, sir, the newborn seahorses cannot be kept in your Biocube or in a refugium. Either of those options would rapidly result in an aquarium that was being overrun by hydroids, which would quickly get out of hand when you began adding copious amounts of newly hatched brine shrimp to your nano reef or refugium on a daily basis in order to feed to seahorse fry. And the dreaded hydroids would then quickly take a grievous toll on the newborns.

Realistically, you would need to set up separate nursery and rearing tanks to have any kind of chance at raising the seahorse fry. When that time comes, I would be happy to help you set up suitable nurseries for the newborns.

Yes, sir — you did it right when you set up your mini reef using primarily mushrooms and polyps, while avoiding SPS corals and LPS 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 and Trachyphyllia, 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

For additional information regarding seahorse-safe corals and invertebrates, please see Will Wooten’s guide to tankmates for seahorses at the following URL:

http://www.seahorse.org/library/articles/tankmates.shtml

Best wishes with all your fishes (and invertebrates), Grant!

Respectfully,
Pete Giwojna

Dear Grant:

Yes, sir — you identified your seahorse as a female in your initial post, and the seahorse in the photograph shows no hint of a pouch whatsoever. Either the pony is a female or it is a juvenile that has not yet reached sexual maturity.

Yikes, Grant — if your nano reef is a 12-gallon aquarium, that’s going to be problematic for anything but the tiniest seahorses. As we have discussed many times on this forum, unless you will be keeping one of the miniature breeds of farm-raised seahorses, such as Hippocampus zosterae, H. breviceps, or H. tuberculatus, it’s best to start with the largest aquarium you can reasonably afford and maintain (the taller, the better). In general, a tank of at least 40 gallons (150 L) is preferable if you’re an inexperienced aquarist since that’s the size when one begins to see significant benefits in terms of the greater stability a larger volume of water can provide. An aquarium of 40-gallons or more will be more resistant to overcrowding and to rapid fluctuations in temperature, pH, and salinity than smaller setups. The larger the aquarium the larger the margin for error it offers the aquarist and the greater the benefits it provides in terms of stability.

It is equally desirable to select an aquarium at least 20-inches high 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 Syndrome.

Under the circumstances, you should not consider adding any Hippocampus erectus to your 12-gallon mini reef. It’s too small to sustain any of the larger breeds of seahorses long-term, and its lack of water depth will leave them predisposed to gas bubble syndrome, which is a fatal condition if left untreated. Adding so much as one more seahorse to the tank would be inadvisable, and your fancy female may be at risk in a tank that size as it is.

It’s unlikely that your seahorses will be able to reproduce in a 12-gallon tank because it is probably too shallow for any of the larger seahorse species to complete the copulatory rise. The shallower the tank, the more difficult coitus is to achieve and the more likely it becomes that eggs will be spilled during the transfer. Eventually this reaches the point where entire clutches are being lost, which is when most pairs cease trying and no longer attempt to breed.

Worse still, shallow tanks increase the danger that an overripe female may become egg bound. In a tank with inadequate water depth, a courting female that has hydrated her clutch may be unable to make the egg transfer, yet she will be reluctant to dump the eggs while a receptive male is still standing by eager to receive them. If she is retains her clutch too long, hoping to pull off the tricky egg transfer despite the lack of depth, she may become egg bound. Her lower abdomen will become very swollen and prolapsed tissue may protrude through the vent as the pressure builds up. If she is unable to release the eggs at this point and relieve the pressure, death will result. An egg-bound female is thus a very serious complication of depth limitations (Leslie Leddo, pers. com.). So you should reconsider trying to find a mate for your female.

The smallest aquarium that would be suitable for a single pair of Hippocampus erectus would be a 20 gallon Extra-High All-Glass Aquarium (20"L x 10"W x 24"H), and a somewhat larger aquarium would really be preferable. If you’re using a 24-gallon Biocube, you could consider keeping a pair of seahorses. But it would be better to stick with invertebrates for your 12-gallon Biocube and then to upgrade to a larger aquarium if you would like to set up a seahorse tank, sir.

Happy Trails!
Pete Giwojna

Dear Grant:

Unfortunately, the list of seahorses that eat frozen Mysis and you can consider keeping in a 12-gallon mini reef is very short.

The only seahorse that Ocean Rider raises that is small enough for a tank that size and that eats frozen foods is their strain of captive-bred-and-raised Hippocampus capensis, marketed under the trade name of Zulu-lulus. Unfortunately, the Zulus like relatively cool water temperatures and would experience heat stress at the temperatures that are suitable for your nano reef, so we need to cross them off the list.

There are three other seahorse species you might consider, Grant — Hippocampus fuscus, H. tuberculatus or H. breviceps. Hippocampus fuscus is a small tropical species of seahorse that is about the same size as H. capensis, but which could tolerate the temperatures in your mini reef. Unfortunately, H. fuscus is difficult to find in this country and is only sporadically available. The short-headed seahorse (Hippocampus breviceps) and the closely related knobby seahorse (H. tuberculatus) would also be suitable for a 12-gallon aquarium. They are miniature Australian seahorses that reach an adult size of about 3 inches in length when they are fully grown — small enough for a tank that size but large enough to eat frozen Mysis as their staple diet. So you could consider a pair of H. fuscus for your 12-gallon Biocube or a small group of H. tuberculatus or H. breviceps.

Ocean Rider does not work with any of these species, but there are some breeders in the US that do. That’s your best bet, Grant — do some searching around and find a source that has H. fuscus or H. tuberculatus available, or that can perhaps provide domesticated H. breviceps that are adapted for the warmer temperatures in your nano reef.

Best of luck finding some small ponies that are better suited for your 12-gallon Biocube, sir.

Respectfully,
Pete Giwojna