Guide to Keeping Healthy Pet Seahorses

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PetMD Editorial
Published: November 16, 2018

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By Kenneth Wingerter

Seahorses are creatures with unique needs that require specialized systems. While coral tanks are popular nowadays due to their compatibility with a whole lot of different critters, for example, seahorses truly belong in “species tanks.”

Though unique in their care needs, seahorses are surprisingly easy to keep (and even breed) if they are maintained in the proper type of fish aquarium system, kept with appropriate tankmates, and offered the right kinds of fish food. Most of all, they can be extremely rewarding to observe and care for. But, before we discuss seahorse husbandry, let’s briefly review their natural history.

Noteworthy Seahorse Facts

Seahorses (Genus Hippocampus) belong to Family Syngnathidae, which they share with the pipefishes and sea dragons. There are about 36 seahorse species in all. These all share a handful of very distinguishing characteristics.

Most conspicuously, seahorses carry themselves in an upright position. They swim using only their dorsal and modified pectoral fins. They do not have a caudal fin (i.e., tail fin); instead, they have a long, strong prehensile tail.

Seahorses do not have scales; instead, their body is armored with a series of tough plates. But it is the horse-like shape of the seahorse head (giving it its common name) coupled with the slender, elongated snout and crooked neck that make these creatures most recognizable.

Seahorses naturally occur in the relatively calm waters of shallow, protected bays and estuaries. They are especially fond of areas with dense growths of seagrass or macroalgae, which they can grab with their tail when tidal currents or wave action is strongest.

Like all syngnathids, seahorses are all strictly predatory. Their favored prey are tiny crustaceans such as copepods, amphipods and juvenile shrimps. Because their prey items are so miniscule,  seahorses must hunt and feed constantly throughout the sunlit hours in order to consume their day’s fill.

Everything it loses on account of its awkward shape, the animal gains back in terms of being adapted to hunt small prey. Though it is a much slower swimmer than most other fishes, the seahorse is capable of impressive maneuverability (it can even hover in place for extended periods of time).

Also, it has a rather unusual means of attacking prey. This mechanism (called elastic recoil feeding) enables the fish to rapidly snap its head forward, using stored energy in certain neck muscles.

Seahorse Tank Setup

The seahorse aquarium isn’t much unlike the sort that one would set up for any saltwater aquarium fish species. Even so, the animal’s life may very well depend upon certain special needs being met.

In some respects, optimal conditions for a good seahorse tank contradict those of a good reef tank. In other words, an aquarium that is well suited for corals is inherently unsuitable for seahorses. Truly, seahorses require their own specialized system!

Because they are not particularly active or territorial, pet seahorses do not really require an especially large tank. What is more important is water quality. Therefore, while you can go a little easy on tank size, you might want to oversize the fish tank filter system.

To be clear, you should oversize the filter on the basis of animal size/number, rather than tank size! That being said, water flow must be kept to a minimum. Moreover, air bubbles should be eliminated to the greatest possible extent.

The aspiring seahorse keeper is certainly off to a good start by using a quality sea salt mix (e.g., Instant Ocean sea salt). To ensure that these sensitive animals are never exposed to toxic ammonia, it is best to start with a bio-active substrate such Nature’s Ocean reef substrate.

One or more simple, hang-on-the-back style filters work well for seahorses; a great example is the popular Marina power filter. Temperature should be monitored regularly with a reliable thermometer such as the Marina floating thermometer.

A “hitching post” is necessary for the animal to hold onto while at rest. There must be enough space on the post(s) for all seahorses in the tank to use. Live (i.e., stinging) corals do not make good posts. On the other hand, seahorses love real or artificial plants/seaweeds (such as Marineland bamboo).

Though they look unnatural, large structures made of material such as PVC pipe can work quite well as posts. Some larger artificial structures such as the Marina mangrove root combine ease of cleaning/handling with a natural look.

Seahorse Stablemates

The most trouble-free way to maintain pet seahorses is to keep only individuals or bonded pairs in each tank. A bit more challenging is keeping small groups of a single species, or herds. It is possible to successfully house different species of seahorses (and maybe other syngnathids) together in the same tank. However, there are limits to this due to differences between each species’ favored parameters (e.g., temperature).

Attempting to keep non-syngnathids with seahorses is yet more difficult. Seahorses, being so slow, simply cannot dodge attacks by aggressive tankmates, nor can they keep up with other types of fish during feeding time.

Feeding Your Seahorse

Feeding is, arguably, where pet seahorses require the most care. To say the least, you should never count on an animal accepting any kind of prepared food (like flakes or pellets). Sometimes, even whole, frozen foods will be rejected.

Tank-bred specimens are better than wild-caught ones, as they tend to be less finicky at mealtime. But by and large, seahorses favor live foods.

Depending on the animal’s species/age/size, this will be smallish crustaceans ranging from copepods to brine shrimp. Smaller, more frequent feedings are better than those that are big but infrequent.

The important thing is to allow the animal to feed well throughout the day. However impractical it may be, it might be necessary to cut the filtration system while feeding.

Of course, each seahorse species has its own, even more special needs. Husbandry and compatibility for any prospective species should be researched fully before bringing a seahorse home. With the proper housing, tankmates and feeding regimen, a seahorse can thrive in captivity for years!