Keeping Seahorses in Aquaria #2 - Aquascaping and Providing Excellent Water Quality

In our first article on Keeping Seahorses in Aquaria, we looked at an introduction to seahorses and setting up a seahorse tank. In this second article of our 6-part series, we will examine the process of aquascaping and achieving the excellent water quality which is so crucial to maintaining the health of our ponies.



I love the process of aquascaping an aquarium. It speaks to both the artist and the nurturer in me. I want my aquariums to have an aesthetic appeal but also to be comfortable for the inhabitants.

There are many different ways to aquascape a seahorse tank but they all include using LR (live rock). It can be used to provide an underwater landscape to display artificial décor, and host living coral or macroalgae. It can be a shelter from high flow or serve as a blind for a pony that is feeling insecure. The LR does not necessarily have to be placed in the display tank if the system has a sump. I know of one keeper who places all of his LR in the sump and uses only artificial décor in his display tank. No matter where it is used or how it is used, LR is the bedrock of the biological filter.

There are 2 ways to acquire LR. The first is to buy it from someone who gets it from the ocean. It is shipped wet and hopefully when it arrives at your door, most of it is still alive. The big advantage of acquiring it this way is that it usually cycles very fast. It can come with lots of neat macroalgae and coral and even invertebrates. The big disadvantage is it can come with unsafe organisms that are not compatible with seahorses, like aiptasia, bristle worms and even mantis shrimp. Most of these can be dealt with by placing the rock in very high salinity before placing it into the seahorse tank. This causes the inhabitants to quickly abandon ship, (or rock) where seahorse safe creatures can be separated from unsafe creatures. Aiptasia or other stinging coral may need to be dealt with by adding peppermint shrimp or killing it with Aiptasia-X or a similar product.


If this sounds too risky to you, then you can buy dead dry rock and cycle it yourself. This process generally requires a lot more time but any unsafe hitchhikers will not take you by surprise. Also since the rock arrives dry, you have the luxury of time to plan out exactly what you would like it to look like in your aquarium. Rocks can be glued or zip tied together before it is ready to be cycled. I will not go into the cycling process except to say, never put a seahorse into a tank that has not been fully cycled!

When adding your now LR into your seahorse DT (display tank), I highly recommend placing it so that it is freestanding. Avoid allowing it to touch any of the sides, not even the back. My reason for this is excess food and detritus can accumulate between the rock and the glass and be difficult to remove or even be seen. You should be able to clean all the glass from the top of the aquarium to the bottom.

Along with LR, you also need to decide about a substrate, or even if you want a substrate. Very coarse substrates like crushed coral are discouraged for seahorses since they run the risk of trapping food. I recommend using a SSB (shallow sand bed) or a BB (bare bottom) for seahorse tanks. A SSB adds biological filtration, plus a very natural appearance. Sand burrowing snails, shrimp and some gobies need a sand bed. A BB display is easier to maintain and is unlikely to deal with unsightly cyanobacteria. Excess food is very easy to see and remove in a BB display. Strong flow can be directed at the BB to help keep particles in suspension until they are filtered out. The biggest reason to avoid a BB is for aesthetics. It does not have the natural look of sand although if the underneath of the aquarium is painted with sandstone paint it can appear somewhat more natural.

Here are a few aquascape examples:



scape 3.jpg

scape mort.jpg

The scape in this pic was designed by @mort

pony NapoliNewJersey.jpg

Another aquascaping example from @NapoliNewJersey
Providing Excellent Water Quality

Seahorses need excellent water quality, but in a different way than a reef tank. Reef tanks thrive when pH, alkalinity, calcium, magnesium, and other elements are kept within the proper parameters. There are test kits to measure the parameters to make sure they are within the acceptable boundaries so that adjustments can be made should they stray. Although pH and calcium play a role in a seahorse tank, the real concern is pathogenic bacteria and parasites. Unfortunately, there are no test kits available to let the aquarist know that these are within the acceptable boundaries. Instead the hobbyist attains excellent water quality through diligent husbandry practices, and “over the top” filtration.

Let’s discuss husbandry first. As an aquarium technician who maintained tanks for businesses and private individuals, I learned the value of consistent WCs (water changes). Nothing helps maintain the stability of a tank better. If you are within the stocking densities, by doing a 25% WC each week, you will be taking an important step toward maintaining excellent water quality for your seahorses. This is best broken up into 2 WCs of 12% or so each week. I am partial to using Instant Ocean Reef Crystals but any quality synthetic salt will work. As I mentioned earlier, pH and calcium play a role in good water quality. Maintaining healthy pH is important in any marine aquarium. Low pH can be an indicator that organics in the water column are pulling the pH down. Also, the macroalgae can have an effect on pH. pH in a seahorse aquarium is important for the same reasons that it is important in a marine fish or reef aquarium. Calcium however is different in seahorse tanks. Seahorses actually need calcium in their water for healthy skeletal bone structure. Consistently maintaining a 20 – 25% WC schedule every week will provide the necessary calcium for a seahorse’s need. This will also keep the pH in the acceptable range if other husbandry is being tended to.

When performing the twice-a-week WCs, this is also a good time to change or clean filter socks, pads, or any medium used to trap excess food or detritus. Left unattended longer than 3-4 days the decaying food and detritus can begin to fuel dangerous bacteria. Once a week all the surfaces that come in contact with the water should be wiped down. Seahorses create a slime coating that builds up everywhere their water touches. I personally like to add carbon passively to my system. I change the carbon once a week. It is also a good practice to use a turkey baster and blow off detritus from all the rockwork, décor, or coral once a week. If your tank has a SSB (shallow sand bed), a portion of it should be vacuumed regularly. Whenever necessary the AIO or sump chambers should be siphoned clean of debris. These husbandry practices are very important in deterring the growth of dangerous bacteria or proliferation of parasites.

The next step in attaining excellent water quality is providing very good mechanical filtration and circulation for your ponies. Years ago, it was thought best to keep seahorses in low flow tanks because they were perceived as poor swimmers. It is true that a seahorse does not have the stamina of other fish but they are much stronger swimmers than most folks think. In the wild, divers have seen seahorses in very swift underwater channels. In our tanks, it is not uncommon to see a pony hitch directly in front of a power head hanging on for all its worth! One of my female ponies swims headlong into the strongest current my tank has, just so she can body surf back to where she started. The flow in that area is around a 1000 gph! Ideally seahorses should have hitches in areas of high, moderate, and low flow. That way they can choose what suits them at any given time.


Check out this pony sitting right in the flow of this pump.

There are 3 main objectives that you want to achieve when planning the mechanical filtration and circulation for a seahorse tank. The first is that you want a minimum of 10 times turnover, but 20 times is better. The more often the water passes through the filtering process the better chance of catching leftover food, detritus or debris. The 2nd is that you do not want any dead spots in the tank. With seahorse tanks being tall, dead spots can likely occur unless care is taken to prevent them. It is important that uneaten food does not settle in these places. It is also important so none of the seahorses go into respiratory distress because they are not getting enough oxygen. Strategically placed power head pumps can effectively eliminate all dead spots. (Take caution when you are choosing power head pumps for your seahorse tank. Be sure the grating is close enough together that a pony’s tail can’t hitch where the impeller is. Many seahorses have been injured in this way. If you have a powerhead pump that you are worried about, you can cover the grated area with wedding veil.) The final objective that you want to achieve is lots of surface agitation. Seahorses are more at risk than other fish to gases building up in the water column if there is inadequate gas exchange. We had already mentioned that tall tanks with small footprints are especially prone to this. This is so important that it is wise to keep an open airline tube along with the return nozzle for surface agitation. That way if the return pump stops, gas exchange is still taking place by the bubbling action from the open airline tube.

There are many options you can choose for mechanical filtration and circulation. For seahorse tanks, I prefer methods that are easy to clean and remove the mediums used to trap food and detritus. If it is too expensive, difficult or complicated, then the chore is likely not to get done as often as it should. Some folks do not recommend canister filters or HOB (hang on the back) pumps for this reason. I personally like a sump with a return pump if it is easily accessible. Only you know if you will perform the husbandry tasks faithfully with the method you have chosen. As long as your mechanical filtration and circulation meet the 3 objectives above and you are diligently attending to husbandry then any method you choose can be successful.

The final aspect of filtering that I am going to discuss is removing the DOC (dissolved organic compounds) from the water column. When a seahorse’s primitive digestive system passes wastes into the water, only some of it is caught by the mechanical filtration. Much of it dissolves and is not caught. This can promote unsightly nuisance algae in addition to being problematic to the seahorse’s health. A large oversized protein skimmer is a very effective way of reducing the DOC. When it comes to seahorse tanks and purchasing a protein skimmer, I say the bigger the better! My protein skimmer is rated for a tank 3 times the size of my system and I don’t think it is overkill. I consider a good protein skimmer a “must have” item for a seahorse tank unless you plan to significantly increase your WC schedule.


A refugium can be a helpful component in your system for reducing DOC.

Another way of reducing DOC is by using a fuge (refugium) with macroalgae or an algal scrubber. Both of these can be effective but I recommend using them with a protein skimmer, not instead of a protein skimmer. With consistent WCs, good husbandry, effective mechanical filtration, and an oversized protein skimmer, excellent water quality should be the result. Happy, healthy seahorses will be the reward.

About author
Dawn Gilson has been keeping fish for as long as she can remember. When she married Dave Gilson they set up a 10 gallon aquarium and then upgraded to a 40 gallon in the wall when they purchased a new house. In 1997 she got hired by the Seahorse Petstore where she worked for 12 years. That is when she began keeping marine fish.
Dawn and Dave have 3 married sons. They passed their love of aquariums to their oldest, Nathan. (Nathan is actually the one who encouraged Dawn to move from a FOWLR system to a reef. Nathan has a 40 gallon reef and is passing his passion of all things aquaria on to his children). Dawn and Dave share their home with a shih tzu and 4 seahorses. They also enjoy motorcycling. The have ridden their bikes in all of the lower 48 states, and still hope to ride to Alaska!

Article information

Last update
5.00 star(s) 3 ratings

More in Saltwater Fish

More from vlangel

Share this article

Cherry Corals Happy Halloween Live Sale! Oct. 26th