A Seahorse Reef, Part Two: Choosing Your Seahorses

Author: Pete Giwojna

In the Part 1 of this article (TFH January 2007) I wrote about how to set up a reef tank that is tailor-made for seahorses, and I discussed which corals are seahorse safe, which corals must be used with caution, and which invertebrates must be excluded altogether from a seahorse reef. This month I will pick up right where I left off and explain everything you need to know in order to determine which species of seahorses are best suited for your particular reef system.

Hippocampus zosterae

Dwarf seahorses are extremely popular here in the United States, and bargain-hunting aquarists might be tempted to consider them for their reefs because they are by far the most inexpensive of all the seahorses. That’s a mistake. Fully-grown dwarfs are barely the size of your thumbnail, and their diminutive dimensions make these miniature marvels very vulnerable to many of the stinging animals that are commonly found in reef systems. Hydroids, Aiptasia rock anemones, large bristleworms, and stony corals are all serious threats to dwarf seahorses. The miniature breeds of seahorses in general have no business in a reef tank and must be strictly avoided.

When considering seahorses for your reef system, stick to tropical seahorses of the larger species (i.e., the greater seahorses) that naturally occur on reefs. Cultured specimens are a must. As a rule, you will find that captive-bred-and-raised seahorses are much easier to feed, have far fewer health problems, and enjoy greater longevity in the aquarium than their wild-caught counterparts. Good candidates include Hippocampus erectus, H. reidi, H. ingens, H. ingens, H. barbouri, and H. kuda. These are all large seahorses that can handle a bit of a current with no problem, and they are readily available from breeders. Any or all of them would thrive at 75°F (24°C) in a modified reef tank brimming with assorted soft corals.

Hippocampus erectus

If I had to limit myself to one of these for a species tank or a seahorse reef, it would be H. erectus without a doubt. Commonly known as the lined seahorse or northern giant, Hippocampus erectus was the first seahorse to be commercially raised for the aquarium hobby. This species has been captive-bred and raised for more generations than any other seahorse, and has now achieved a level of domestication that makes it better adapted to aquarium conditions and life in captivity than other seahorses.

These are impressive animals. They are large, robust, deep-chested seahorses that will approach 10 inches in length when fully grown. Best of all, cultured erectus are now available in a number of attractive color morphs, such as bright yellow, fiery red, and specimens with a piebald color pattern.

Characteristics and Behavior

The first captive-bred seahorses I ever owned were H. erectus, and my original pair is still going strong after all these years. They quickly learned to recognize me as their feeder, and soon they were literally eating right out of my hands. (I know, I know, sensible aquarists should always strive to keep their mitts out the aquarium as much as possible, but hand-feeding is a thrill I find difficult to resist—and hey, nobody ever said I was sensible!)

Nowadays they head for the feeding station as soon as I approach the tank, a series of color changes betraying their excitement, and queue up at the dinner table looking their best and brightest. Of course, they both try to snap up the first morsel—even pair-bonded ponies are not big on sharing or waiting turns—so I no longer offer them one mysid at a time.

I offer them a handful of individually thawed mysis in my upturned palm instead. They know the drill and happily perch on my fingers while snicking up the shrimp as fast as they can. They genuinely appear to enjoy interacting with me and like to linger on my hand long after all the food is gone. They would allow me to lift them out of the water when I withdraw my hand if I didn’t gently shoo them away first. There’s a lot of puppy dog in your average seahorse, and H. erectus is no exception; one almost expects to see them wagging their tails as they beg for handouts.

Water Requirements

However, H. erectus does best at cooler water temperatures, around 75°F (24°C). Many seahorse keepers run modified reef tanks featuring soft corals that do well under relatively low light levels and relatively cool temperatures within that comfort zone, and it is these systems in which the highly domesticated Hippocampus erectus excel. Other reefers who use high-intensity lighting install aquarium chillers on their systems to avoid overheating, and such reef tanks would also be a good choice for H. erectus.

But if like most reefers you are operating a traditional reef system with high-intensity lamps and water temperatures in the 80°F (27°C) range, you may be better off with one of the reef-dwelling seahorses that likes it hot, such as H. ingens, H. barbouri, H. comes, H. kuda or H. reidi. These species are all comfortable at temperatures in the 78° to 82°F (25° to 28°C) range.

Hippocampus reidi

The ever-popular Brazilian seahorses Hippocampus reidi are sleek, graceful animals, perfectly proportioned with slender bodies, long tails, and long snouts. Their lithe appearance gives rise to their other common names, the slender seahorse or the longsnout seahorse. Whereas the robust H. erectus is solidly built, like a truck, H. reidi shares the graceful curves of a Corvette stingray. The result is an elegant warm-water seahorse that is an all-time favorite.

Long renowned for their brilliant colors, rapid color changes, prolific breeding habits, and huge broods of difficult-to-raise fry, all serious seahorse keepers are familiar with these breathtaking beauties. Often proclaimed the most attractive of seahorses, H. reidi is the crown jewel in many aquarists’ collections. These rather majestic steeds are long-lived, and with good care they will be your companions for the next 8 to 10 years, and may eventually reach a length of 7 inches.

This species regularly produces some of the most brilliant color morphs I have ever seen. Going from most to least common, these sports include bright yellow, orange, and red individuals, which are much sought after by aquarists. The yellow, orange, and red morphs of H. reidi have all been established by aquaculturists and are now readily available.

Hippocampus ingens

The closely related Pacific seahorse H. ingens is accustomed to equatorial heat and is another good choice for warmer reef tanks. Hippocampus ingens are true giants among the seahorses. They can reach a length of 36 cm, or more than 14 inches, when fully grown, making them the world’s largest seahorses, rivaled only by the biggest examples of H. abdominalis. The prehensile tail of a large adult has a powerful anaconda-like grip, and they can exert enough pressure to leave you counting your fingers afterward when they squeeze down. As you can imagine, when fully grown, they have no problem handling brisk currents in a reef tank.

But despite their great size and power, these gentle giants are not at all the brutes you might imagine. They are close relatives of the Brazilian seahorse H. reidi, and they share its slender profile and graceful proportions. Imagine a seahorse with the same sleek silhouette as reidi, but which reaches twice their size, and you will have a pretty accurate impression picture of H. ingens. They are stately steeds, built like thoroughbred racehorses, and they carry their size very well. The crowning touch for the king of all the seahorses is a tall, backward-swept, five-pointed coronet, which adds to their majestic appearance. The Hawai‘ian strain of captive-bred ingens is a bright golden yellow, often further adorned with a lacy latticework of vivid purple-to-lavender lines.

On the other hand, H. comes and H. barbouri are better choices for reef systems that feature hard or stony corals. They are reef dwellers that are accustomed to living on and amongst hard corals. As a result, they are naturally reef-savvy seahorses that know which stony corals make good holdfasts and which should be avoided.

Hippocampus comes

Tigertail seahorses Hippocampus comes are among the most beautiful and boldly marked of all seahorses. Their beauty is not due to vivid colors, but rather to their striking pattern and graceful proportions. They are sleek, slender seahorses built like greyhounds. With their long snouts and slim profiles, these smooth-bodied creatures seem almost streamlined. Their elegant proportions and bold stripes make tigertails highly prized by all seahorse keepers.

As you might expect from their common name, a beautifully striped tail is the trademark of Hippocampus comes. Many tigertails also display an attractive mottled or blotched pattern on the body with a network of fine white lines radiating from the eye. In the best specimens, the contrasting bands on the tail extend well up onto the body in the form of alternating light and dark blotches. Well-marked yellow-and-black H. comes are particularly striking—when the yellow is bright, they look especially tigerish!

Hippocampus comes is one of the few seahorse species that has been studied in the wild. Field research shows that they are reef animals that select a favorite piece of coral as their home base, and they seldom stray from that tiny patch of reef thereafter. H. comes evidently prefers living amongst stony corals because they serve as good holdfasts, provide crevices for protection from predators, shelter the seahorses from currents and wave action, and are prime microhabitats for the small crustaceans they prey upon. Needless to say, tigertails feel very much at home in a reef tank filled with SPS corals.

Hippocampus barbouri

The prickly seahorse Hippocampus barbouri is equally well-adapted for a reef system with hard corals. In fact, H. barbouri is said to be impervious to the stings of stony corals. Barbs prefer warmer temperatures than most other seahorses and are the perfect choice for a reef tank that includes LPS and SPS corals.

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 the name to H. barbouri. They are readily identified by their sharp, well-developed spines, their prominent five-pointed crown, and their boldly striped snouts. 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.

Feeding

No matter which species of seahorse you select for your reef tank, 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 an intricate reef 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 will lodge in isolated nooks and crannies where the seahorses cannot get it. 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 later on and eaten after it has begun to spoil. Either outcome can have dire consequences.

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 “Feeding Stations: A Better Way to Feed Seahorses” in Conscientious Aquarist, at www.wetwebmedia.com, for a detailed discussion explaining exactly how to set up a feeding station and train your seahorses to use it.)

Coral Feeding Troughs

You’ll find that many of the live corals in your reef make superb natural feeding troughs for seahorses. For example, cup coral and toadstool leather corals work great for this. The bowl-shaped contours of these corals contain the frozen mysis nicely while the seahorses perch around the edges and scarf up the shrimp as if dining at a breakfast bar.

Target-Feeding

But 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 the mysis while it’s swirling through the water column, and some will only take it 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 food 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 swimmers gobbling up all the goodies before the slowpoke seahorses can grab a mouthful? Target feeding is the answer. Target feeding simply 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 this way makes it easy to keep track of exactly how much each of your specimens is eating.

Methods of Target Feeding

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.

A great number of utensils work well for target feeding. I’ve seen hobbyists use things such as chopsticks, extra long tweezers, hemostats and forceps, and even homemade pipettes fashioned from a length of rigid plastic tubing. As for myself, I prefer hand-feeding when I target feed a particular seahorse.

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, holding the tempting morsel right in front of the seahorse’s mouth as long as necessary. 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. (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 ensure 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.

The key to successfully keeping active specimens like firefish or cleaner shrimp 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. And there are indeed plenty of reef-safe fishes that make good companions for seahorses.

Compatible Tankmates

When selecting reef-safe fishes as companions for seahorses, the aquarist must avoid fin nippers and aggressive, territorial fish that would be inclined to bully or physically abuse them. This includes damsels, angelfish, most clownfish, triggerfish, dottybacks, puffers, cowfish, and the like. Piscivores and predatory fishes such as lionfish, anglers, sargassumfish, rays, large groupers, and morays are likewise unacceptable for obvious reasons.

Food Competition

Aquarists that are accustomed to catering to the demands of delicate wild-caught seahorses also scrupulously avoid peaceful fish that are active, aggressive feeders (e.g., butterflies, tangs, and small wrasses), and rightly so. It is difficult enough to come up with sufficient live food for wild seahorses in the first place, and active fishes would greedily dart around the tank and busily scarf up all the live food before the horses got much more than a taste. But that is no longer the case with cultured seahorses that are born and bred for life in the aquarium and are accustomed to eating frozen foods. This means the feeding habits of potential tankmates need no longer be an overriding concern.

Although competition for food is always an issue with seahorses, it is no longer a sufficient reason to automatically exclude entire categories of fish as potential tankmates. Nowadays, domesticated seahorses are often kept with otherwise gentle fish that are aggressive eaters, and it is standard operating procedure to deal with the situation by target feeding the seahorses as previously described.

Essential Tankmates

In general, farm-raised seahorses will do great with blue and green Chromis, Grammas, pipefish, jawfish, firefish, assorted gobies and blennies, cardinalfish, most reef-safe wrasses, and many others. As always, any potential new tankmates should be rigorously quarantined before they are introduced to the mini-reef.

Caution: Clownfish

Clownfish meet many of the criteria for suitable tankmates, but should generally be regarded with caution. Most species, such as tomato clowns Amphiprion frenatus, maroon clowns Premnas biaculeatus, and skunk clownfish, are surprisingly aggressive and territorial and should be shunned on that basis. Others do best when kept with anemones, which are a threat to seahorses. All clownfish are prone to Brooklynella and marine velvet (Amyloodinium), and should be considered ich (Cryptocaryon irritans) magnets as well. The only clownfish species I would recommend as companions for seahorses are the perculas Amphiprion percula and false perculas A. ocellaris. Both should only be introduced after a lengthy quarantine period, and captive-bred specimens are best.

And if your reef system is already home to incompatible corals or a fish or two that might be problematic for seahorses, there are other possibilities for keeping these amazing aquatic equines you can explore, such as adding them to your refugium.

Seahorses in the Refugium

Another popular option for reefers who fancy seahorses is to keep them in their refugium rather than the main tank. This allows them to enjoy seahorses and still maintain a traditional reef system replete with all the LPS corals, colorful Tridacna clams, and anemones they desire. It eliminates the need to seahorse-proof their reef tanks, and Hippocampus will often thrive in a properly designed refugium with adequate height. Confining the seahorses safely to the refugium seemingly enables the reefer to enjoy the best of both worlds.

But there are a couple of drawbacks to this approach. Seahorses can rapidly deplete the population of copepods and amphipods within such a confined space, which defeats one of the primary purposes of establishing a refugium. This can be counterproductive if the aquarist is relying on his refugium to seed the main tank with pods or to provide larval crustaceans and zooplankton for their corals and reef invertebrates.

More importantly, most refugia lack sufficient height to be suitable for seahorses. Seahorses need vertical swimming space in order to complete the copulatory rise and transfer of the eggs, and they are susceptible to depth-related conditions such as gas bubble syndrome (GBS), a potentially fatal affliction caused by gas emboli forming within the seahorse’s blood and tissue. The greater hydrostatic pressure at increased depth is known to protect seahorses against GBS, whereas the reduced hydrostatic pressure in shallow aquaria is known to be conducive to GBS. For this reason, tanks that are at least 20 inches tall (the taller the better) are preferred for a seahorse setup.

Shallower aquaria may prevent successful breeding and result in chronic problems with subcutaneous emphysema, pouch emphysema, or other forms of GBS. The typical refugium is simply not the best choice for the long-term health of seahorses.

But if you can design a refugium that’s tall enough, and you don’t mind if they make a serious dent in your pod population, then seahorses should flourish in your refugium.

Final Tips

In summation, keep the following guidelines in mind when selecting seahorses for your reef system:

1. Avoid wild-caught seahorses at all costs! Stick with hardy, easy-to-feed cultured seahorses that are well adapted to aquarium life and trained to eat frozen mysis as their staple diet. Avoid dwarf seahorses H. zosterae and the other miniature breeds of Hippocampus.

2. Target the larger species of tropical seahorses that naturally occur on reefs, such as H. erectus, H. reidi, H. ingens, H. comes, H. barbouri, and H. kuda.

3. The highly domesticated, tough-as-nails Hippocampus erectus can’t be beat for modified reef systems with soft corals and moderate temperatures (75°F or 24°C).

4. Traditional reef systems that consistently run around 78°F to 82°F are best reserved for seahorses such as H. ingens, H. reidi, H. comes, H. kuda and H. barbouri that prefer warmer temperatures.

5. Reef keepers that prefer SPS and LPS corals should strongly consider reef specialists such as H. barbouri and H. comes that know their way around stony corals.

Whether you prefer soft corals, stony corals, or a mixture of both, one of these tropical seahorses should be ideal for your reef system. Happy seahorse-reefkeeping!

Chart of Compatible Tankmates for Seahorses