Keeping Seahorses in Aquaria #3 - Stocking Your Seahorse Tank: What to Add Other Than the Ponies

In our previous article on Keeping Seahorses in Aquaria, we examined the process of aquascaping and achieving the excellent water quality. In this third article of our 6-part series, we will explore options for stocking your seahorse tank (looking at options other than the ponies themselves). This will include things like CUC (clean-up crew), corals, macroalgaes, fish, and other livestock.


Once your aquarium is set up, filled with synthetic saltwater where the salinity is between 1.023 and 1.025 specific gravity, and the LR is in and fully cycled, then you are ready to add a CUC . This is a good time to seed the aquarium with copepods and amphipods, especially if the system has a fuge where they can propagate without being preyed upon by the ponies. If the system does not have a fuge then it is wise to give the pods at least several months to get well established before adding seahorses.

With seahorses, most crabs are considered unsafe, since an inadvertent pinch could start a skin infection. The one exception to the ‘no crab rule’ is the small red or blue-legged reef crabs. All other crabs are a risk.

Snails are a good choice. Trochus, nerites, ceriths, astrea, and nassarius all can be a tremendous help in a seahorse aquarium.


Some cleaner shrimp, particularly peppermints can be a great addition to a CUC. Other cleaner shrimp can be a bit overzealous about cleaning the seahorses and this can be stressful to some ponies. Peppermint shrimp usually do not do this and are excellent at finding trapped food and keeping the aquarium clean of decaying mysis. Some specimens also will eat any aiptasia that might pop up. Just be sure to choose larger specimens, or your ponies may view them as an expensive dinner rather than part of the janitorial staff!


Nudibranchs, sea hares, and cucumbers can all be safe choices if there is no possibility of them being sucked into a power head pump or suffer some other violent death. If they are traumatized they can give off a toxin that can poison the tank, so consider this risk before choosing one. Also, research to make sure that your tank can sustain the creature of choice. Many varieties quickly deplete a tank of the food that they eat and then suffer a slow starvation.

It is best to buy only a small amount of CUC at this stage since the aquarium is only beginning to get established. Start small and add as there is a need for more CUC. Many online vendors send out premade packages of CUC that contain more creatures than necessary for newly set up tanks. If your CUC is too large, then after a couple of weeks when all the algae in the tank is consumed, many of the organisms perish from starvation. Worse still is their decomposing bodies cause a chain reaction that can actually result in more algae!

This next section has to do with adorning the seahorse aquarium with appropriate foliage, coral or artificial décor. Things to keep in mind are that seahorses spend much of their time hitched and so they should be provided with lots of hitches to choose from. Avoid anything that is sharp and could potentially cut or pierce the ponies’ skin.


Seahorses are influenced by the colors of their surroundings. Hitches chosen in bright yellows, oranges, reds and other colors can possibly encourage those colors in your seahorses. It is not a sure thing because it also has to do with the natural pigments that a seahorse has along with hormonal and other environmental factors. For instance, stress can very definitely impact your ponies’ color. Most seahorse keepers enjoy seeing their herd displaying vibrant colors and choosing colorful hitches can help.


When adorning the seahorse tank the aquarist must decide whether they will use artificial décor, live coral, or a mixture of both. Much of this decision depends on the preferences of the aquarist.

Artificial décor can be very realistic in appearance and natural looking without the hassles of providing the right lighting, food and proper flow. It can be easily cleaned when necessary and is generally more budget friendly than live coral. A tank with artificial coral can immediately have a mature established appearance.


Some aquarists enjoy keeping coral and macroalgae almost as much as fish. They like the natural appearance and the challenge of meeting the needs of live coral and macros. This can add a very satisfying element to keeping seahorses but it does require keeping in mind that the needs of the seahorses must come first. For instance, not all coral are seahorse safe. Seahorses should never share a tank with stinging coral of any kind. Also, the needs of some coral may conflict with the needs of the seahorses. Never compromise the needs of the seahorses to accommodate a particular coral. Good corals to choose for a seahorse tank are leathers, palys, zoas, most mushrooms, xenia, green star polyp, clove polyps, duncans, blastos, pagoda cup, and gorgonians. Most of these are hardy and will thrive in cooler water temperatures. Most macroalgae are seahorse safe and will also do well in water temperatures suitable for ponies. The biggest concern with macroalgae is that it be kept pruned and controlled. Husbandry must be extra diligent when keeping live coral and macros because excess food and detritus can be caught or trapped in them. It is advisable to use a turkey baster or powerhead to blow off all rock, coral and macros at least once a week.


Seahorses can share accommodations with some fish if precautions are heeded. These fish should be quiet, gentle species—like gobies, some blennies and some cardinalfish. Quick darting or aggressive species are to be avoided. The ponies could be stressed by the fish’s constant movement or even have trouble competing for food. Seahorse.org has a list of potential tankmates for seahorses and they are rated on a scale. This can give you guidance when choosing tank mates. Additionally, I would add everything discussed in this article before the ponies except the fish. Even gentle fish can be a bit territorial, but most fish respect inhabitants who resided in the tank before themselves. So, any fish additions should be added after the ponies.


Another important practice when adding any fish is to properly QT (quarantine) it to assure that it will not introduce pathogens to your ponies. All fish should go through a process of QT for at least 7 weeks to make sure they are pathogen free. CB (captive bred) seahorses have not been exposed to the pathogens that WC (wild caught) fish have. Even CB fish from a different source should be QT’d. This is a very important practice if you want to keep your herd healthy. Remember, seahorses are at a disadvantage when fighting off any diseases!

You now have a beautiful aquarium that is perfectly adapted to provide a wonderful home for seahorses. All you need are ponies to make it complete!