by Richard Rayl
Pictures provided by Lam Kuduro
Aquarium hobbyists are often on the lookout for unique animals to stock in their miniature ecosystems. We like to look for striking colors, unique personalities, or differing physical forms to accent and complement our tanks. Nothing fits these descriptions more aptly than seahorses. Their otherworldly shapes are completely unheard of when compared to other common aquarium fish. The seahorse is almost mythical in design, with its horse like head strangely mated to an armored, serpentine body. Seahorses are fantastic creatures to observe in aquaria, and with a little advanced planning and research, not much more difficult to keep than many other fish. I hope this article will dispel some of the mystery behind seahorse keeping, and demonstrate the basic requirements for building and maintaining a stable environment so even a “beginner” aquarist may enjoy these fascinating – and beautiful – animals.
Seahorses were once considered to be very difficult animals to keep. At one time, seahorses were only caught in the wild. Wild specimens usually only lasted a few months in a home aquarium before succumbing to infection or starvation. Recent years, however, have produced a breakthrough with seahorse keeping – that of the captive-bred seahorse. Captive bred horses outshine their wild brethren in many different ways. They are weaned on frozen prepared foods, they are hardier to a wider range of environments, and are almost always disease-free. Finally, and probably most importantly, captive bred seahorses are not removed from the wild, so we are not contributing towards the depletion of a natural resource!
I was first introduced to seahorse keeping by my wife. We were entertaining the idea of a new aquarium in the house, and she mentioned in passing that she’d always wanted seahorses when she was a kid. I’d never even considered keeping horses, but her comment got me thinking. What would I need to successfully keep these odd-looking fish?
Photos provided by Kelly Delavergne
Seahorse BasicsThere are many different species of seahorse available to marine aquarists these days, and some species have very different requirements for their environment. Most common horses you will see will reach a similar full grown size; that is, 5-8 inches in height. For now we will focus on these normal sized horses; specifically, H. erectus, H. reidi, and H. barbouri.
First, we should look at a seahorse’s anatomy. Seahorses are relatively lower on the evolutionary scale than most bony fishes, and there are a few differences we should know that will affect how we keep these animals. First, and perhaps most importantly, seahorse gills are far less efficient than those of other bony fishes. Their method of gas exchange is limited compared to other bony fish. Also, seahorses lack true stomachs. Food is passed through their digestive system with surprising speed. Because of this, they have to eat more often to maintain their energy levels. Finally, seahorse keepers should keep in mind that horses lack scales. Instead, their structure is based on an exoskeleton that is covered with skin-like tissue. Because of this, seahorses are sometimes more prone to bacterial or viral infections, and sores on the skin are a threat the aquarist should be aware of. Finally, a seahorse’s mouth is uniquely different from almost every other bony fish. This elongated snout is regulated by a “suction gun” effect, which is adapted to suck small prey in at remarkable speeds. Do not be fooled by their small mouths, however. I have seen 4 inch seahorses attack and consume small shrimp more than half an inch long with little difficulty!
The Tank Now that you’ve decided to keep seahorses, you should really start with a new tank. There are too many factors to consider, too many restrictions to abide by, to try adding seahorses to an established aquarium. First, consider the size of your tank. Seahorses are vertical animals, and utilize the water column to its fullest extent. In other words, the height of your aquarium is just as important as its footprint is. Find a tank that is at least 18 inches tall; the taller, the better.
I chose a 37 gallon “tall cube” for my seahorse environment. This gave me a roughly 19’ by 19” footprint and 24 inches of height for the horses to play with. A tank this size, properly filtered, will be an adequate home for 3 or 4 seahorses without causing them stress, or 2-3 horses if you plan on adding a different fish or two. The standard fluorescent strip light that comes with most aquariums is sufficient for seahorses in most cases. Seahorses don’t like as much light as a normal reef tank would provide, which is a factor you must take into consideration if you wish to have a couple corals in the tank as well.
Controlling the temperature of a seahorse tank is also important. Seahorses prefer cooler waters than most tropical aquaria, so the tank should be kept cooler for their maximum comfort. A tank temperature of 74 to 76 degrees Fahrenheit will be suitable. Most of the time, this cooler temperature can be controlled by running a fan over the top of the tank, but you may want to explore a chiller if you live in warmer climates. Other parameters, such as pH, salinity, and nitrogen cycle readings, should all be kept as close to FOWLR settings as possible.
Author's 37 gallon cube tank along with his prized seahorse.
Filtration Filtration is a hotly debated topic in any aquarium setting, and seahorse tanks are no different. A good quality HOB style filter will be suitable for seahorse tanks, even preferable in some ways. Seahorses should not have a large amount of flow in their environment. They are relatively weak swimmers, and would be buffeted constantly by the flow of a strong canister or most overflow style filters. Overflow filters are a good option, provided the return flow is not too strong for the tank size. If you do choose a HOB style filter, you will need one that is rated for a larger tank than you will be keeping. Because of their primitive digestive systems, a single seahorse can create a large amount of undigested food that essentially passes straight through their gut, only to decompose in the aquarium. Filtering this out becomes a full time task. Water movement from a lower-flow HOB filter also becomes an issue. With reduced water current comes reduced O2 saturation. A seahorse’s primitive gills have a very hard time getting enough O2 from their environment, and in fact will die from hypoxia in tanks with inadequate filtration. Low flow also has the possibility to produce dead zones, or extremely low oxygenated areas of the tank.
A simple and elegant solution is available in the form of a protein skimmer. Not only will a skimmer help reduce nitrates and skim out excess organics, it will help aerate the water and increase the aquarium’s oxygen content. Simply put, a protein skimmer – even an inexpensive one – is an essential ingredient to seahorse aquaria. Another option you can consider is the addition of a single low flow powerhead. The commonly held belief that a seahorse cannot tolerate any current is a misconception; on the contrary, a healthy horse can handle quite a strong flow if it has to. I should stress that last point: if it has to. The idea of watching seahorses zooming around your tank or surfing the current may be amusing to consider, but not recommended for the horse. Rather, a small powerhead near the bottom or back of the tank is enough to generate a gentle current that will eliminate dead zones and still not stress your seahorse.
Tankmates and Environment A seahorse tank is going to be set up slightly differently than a FOWLR or reef environment, but the differences are only minor. First, you may have heard the old story that seahorses need species-only tanks. “Don’t put other fish in ‘em!”, I’ve heard rumbled around in some stores, and “All corals will kill seahorses!” has also come up from time to time. Nonsense, I tell you.
While it is true that keeping horses with other tankmates requires a good deal of advance planning, it is not difficult at all to find many species of fish, invertebrates, and corals that will be acceptable. There are plenty of online references to help plan your tank, most notably at www.seahorse.org, but here is a barebones list of what you may expect to add to your seahorse tank:
Fish: There are many slow, cautious fish that make excellent tankmates for seahorses. Scooter Blennies, firefish, Banggai and Pajama Cardinals, and Royal Grammas are generally considered safe to keep. Many small goby species are acceptable, and special fish like the Catalina goby are an excellent addition to a chilled seahorse tank. The key to keeping other fish with your horses is their activity level. Fish that have a high activity level will easily out-compete the seahorse for both food and swimming space. Although fish add visual interest and diversity in a seahorse tank, I strongly recommend that you start with your seahorses and add only a couple fish from this list afterward. Let the horses get used to their environment before introducing strangers, so the fish don’t become territorial.
Invertebrates: Most snails are fine for seahorse tanks, and in fact recommended. Small hermit crabs like the blue-legged varieties are acceptable, and help clean up any leftover food. Most other crabs are best left out of a seahorse tank, as they might try to nip at a horse’s tail. Shrimp are also usually left out of a seahorse setup. Small shrimp would likely become food for the seahorse, while larger shrimp may outcompete for food. Finally, anemones of any kind have absolutely no business in a seahorse environment.
Seahorses in the same tank with peaceful firefish in the background. Picture provided by the author.
Corals: A very hotly debated topic these days is whether you can keep seahorses in a reef environment. My answer is generally “no”, but with a twist. You may not keep many seahorses in a reef tank, but you can keep quite a few reef denizens in a seahorse tank! First, consider your lighting. Seahorses usually prefer lower light levels, so choose your corals accordingly. Also, any large tentacle LPS corals should definitely stay out of seahorse tanks. A good rule of thumb is if it looks like an anemone, it will act like one. Large LPS corals have great numbers of stinging cells that can and will hurt the delicate tissue of a seahorse’s hide. These restrictions still leave a large number of corals to choose from, however. Polyp corals are generally fine to keep with seahorses. Gorgonians are often the classic seahorse decoration, and do well with a little specific care. Mushroom corals and Ricordias are also generally acceptable. Finally, faux corals are becoming more popular as new varieties come to market that almost exactly match the real thing.
Hitching Posts: Seahorses need structure of some kind to hitch on to during the day. Most of their days are spend with their tail wrapped around some easy to grab spot, swiveling their independent eyes in every direction to try and hunt for food. Gorgonians are excellent for this behavior, as are many faux corals and kelps. My two yellow reidis spend most of their day in a red kelp that I have “planted” in the back corner of the tank. In the evenings they migrate to the yellow and orange Gorgonians near the front of the tank, often with their little faces trained right on me as they wait for their supper.
Photos provided by Tom Robinson and Lam Kuduro
Care and FeedingThe single best food for captive bred seahorses is frozen mysis shrimp. Horses love ‘em. Because seahorses are such slow, methodical feeders, you must decide how best to present the food to them. You can hand feed them with a little patience, spot feed a few shrimp in front of them, or set up a feeding station for them to go to. In most cases, your best friend is going to be a glass turkey baster. With the baster you can present shrimp one at a time in front of the animal, suck them back up if the horse doesn’t take it, or carefully deposit a larger amount of shrimp in the feeder station. Most seahorses should be fed 6-8 shrimp each twice a day. Larger horses will eat more, so observation of your animals is important.
Although I love hand feeding my seahorses, I find the feeding station is much more convenient. A feeding station consists of any cup-like object that the horses can come up to. I use a small clear glass culinary prep bowl, but I have seen people use many different items. Large empty shells will do, flat depressions in a piece of live rock, even plastic suction cup store bought feeder stations will work. You should provide some hitching posts around the cup for the seahorses to latch on to. In order to get them started with a feeding cup, you should get the horse’s attention with a single shrimp, and then guide it over to the feeding station. Usually you will only need to do this once or twice before they catch on. Soon you will see them motoring over to their feed bowl as soon as they see you walk in the room!
Food that author uses and recommends. Mysis shrimp from Piscine Energetics.
Health and Disease PreventionI have been asked before about a certain seahorse’s coloration. Color varies from individual to individual, rather from species to species. There is no species of “yellow horses.” I have seen yellow H. reidis, yellow kudas, and yellow erectus horses! The color of a seahorse will change depending on its mood, stress level, and environment. My H. reidis are usually medium yellow banded with brown stripes, but when my male is courting the female he changes to a bright yellow, and his stripes become highly pronounced. When I first introduced them to the tank they both lost most of their yellow coloration, assuming a mottled brown that blended in with the live rock. The bottom line is simple: don’t buy your horse on color alone! You should observe any color changes in your horse when you have him home, because a radical color change may be the result of a stressed animal.
Seahorses are prone to most of the same ailments as other fish. The diagnosis and description of seahorse disease could fill a full volume by itself. Detailed diagnosis and care articles are available online with a quick internet search. To cover the basics, however, you should remember that seahorses, despite being so visually different, will occasionally come down with the most common of marine parasites….ich. The best cure for ich is, of course, prevention, so you should be vigilant and quarantine any animal that goes in to your system. Seahorses are also prone to develop skin lesions from time to time. Remember, seahorses do not have scales, and the possibility of a bacterial infection is that much more increased if a horse’s hide is scraped. Be prepared with a small hospital tank on hand if you need to remove and treat a seahorse. The links below will help guide you if you encounter a sick seahorse.
And Now……You have your own seahorse tank! I hope this guide has been helpful to you. Although a seahorse aquarium requires a little more work to start up, the benefits of the finished product far outweigh the initial planning required. Seahorse aquariums are at the same time both incredibly relaxing and completely enthralling. Don’t be surprised when you find yourself spending time sitting in front of the tank, just…watching. After all, your seahorses will probably be watching you back.
Photos provided by Lam Kuduro, Shane Gehring, Kelly Delavergne
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