This fact sheet is provided courtesy of The Seahorse Sanctuary, Kalbarri, Western Australia.

The following information is intended only as guidelines for seahorse tank set up. These guidelines are brief and don't include how to set up a marine fish tank as this information is already available in any good marine tank book or retail outlet. If you haven't set up a marine tank in the past then as a new seahorse enthusiast, you'll find that you get the best results if you learn about basic marine tank set up for yourself as you're the best person to care for your seahorse. Your seahorse looks to you to correctly maintain their environment.

SeahorseTank Size

We recommend bigger rather than smaller, preferably a tank that is between 150L to 200L of seawater. The temperature in smaller tanks will have a higher variation between night and day. Your seahorse will be less stressed with a more constant environment where the temperature doesn't fluctuate. Yes your seahorse can cope with temperature variation in the short term, but for a happy, healthy, long life, stress free is the key! 

Stocking Density

We recommend no more than one seahorse per 25 - 30L of water taking into account the above minimum tank size. Any more animals than this and your water quality will be less than ideal. In general you will need to change the half of the water in your tank every 2 months. Again, less stress is the key, so heat up the new water to the correct temperature before adding to your seahorse tank. 


Give thought to where you set up your seahorse tank before you fill it with water. Once filled, it is difficult to move. Avoid positioning your tank close to a window. Too much sunlight is a stimulus for algae to grow and excessive cleaning of the glass will be needed. In addition, if the window that your seahorse tank is in front of gets afternoon sun, then your seahorse tank will most likely over heat in summer. Place your tank away from windows.

Although we have bred many species of seahorse over the years, for the pet industry we only breed tropical seahorses. These have proven to be the easiest temperature to maintain for the home hobbyist. Please remember, however, that in summer when the temperature in Australia can reach 45C, your home tank will heat up past tolerance point for tropical seahorses. So position your home tank in a room with air conditioning for those hottest days. Avoid putting tanks close to heaters/fires and in the direct draft of air-conditioners.

Tank Mates

Live rock is not recommended. Live rock has many benefits in home aquaria however it is not essential. On the positive side it provides biological filtration, but on the negative is can harbour dangerous animals. Caution is required before adding live rock to aquaria as it often contains animals that will harm your seahorse, particularly shrimp, crabs and stinging polyps. Live rock also provides a mostly dark brown coloured background that will cause your seahorses to lose their bright colours in order to blend in and will become dark brown. We have had a great deal of feedback on this point over the years which compels us to recommend other forms of filtration that are available in petstores.

Remember that however big your tank is, your seahorse is in a confined area together with tank mates that you choose. Most salt water fish are aggressive or too quick and will beat your seahorse to the food. In addition, most of the other salt water fish are wild and so can carry the risk of disease that may affect your cultured, disease free seahorse. For these reasons, the only species that we recommend for our cultured seahorses are those that we breed. See our photo gallery for other cultured seahorse friendly species.

Corals generally need high flow rates, which are incompatible with seahorses. In addition, some have stinging cells that can affect your seahorse.
Anemones have stinging cells that can affect your seahorse and so are not recommended. Crabs and shrimp with big nippers, can also harm your seahorse.

Water Source

In most major cities in Australia, home delivered salt water is available. This takes all the pain out of saltwater aquarium keeping and is simply the easiest way to go. If this isn't available to you, artificial sea salt can be purchased from your pet store. As long as your tap water is good quality and you are careful to follow instructions correctly, artificial seawater is a good alternative. Salt water from the ocean is also an alternative, but needs to be treated prior to use in your tank as per marine keeping books. 

Water Parameters

Use a floating hydrometer to maintain salinity 1024.0. Measure this once a week and top up with de-chlorinated fresh water as necessary to keep the salinity relatively constant. Remember, your seahorse wants a stable environment and looks to you to maintain it. 


Maintain between 7.9 - 8.4

Don't stress too much over pH. Relax - your seahorse will tolerate pH 7.9 indefinitely with no trouble. They have been raised for many generations at this pH. If it drops below this point, and your tank isn't overstocked, its time to do a water change. Basically if you keep to our stocking density recommendations, and do water changes every 2 months, your tank pH should never become a problem.


25C - 28C. Your seahorse will tolerate up to 32C, but no fish will tolerate rapid and continual change. To keep your seahorse happy, again, less stress is the key. Try to keep the temperature stable and avoid any sudden changes in temperature that may occur from things like a water change, a cold night or a hot day. 


Nil. This is perhaps the most important parameter and should be measured daily during tank setup and then at least once a week once your tank has been established. Your seahorse will tolerate small amounts of ammonia (i.e.0.5mg/L) for a short time (a week or two), but prolonged exposure to low levels of ammonia will cause stress, which may result in disease. The answer is to "age" your tank for 6 - 8 weeks before adding your first seahorse in. Then the key is to do it slowly. The temptation is to stock your tank with lots of seahorses straight away. Avoid this at all costs - sudden overstocking of your tank will cause an ammonia level to increase, causing distress to both you and your seahorse. Initially buy one seahorse - wait several weeks and when the ammonia level drops to zero, add another. Continue until you have reached the stocking density we recommend - no more. 


These will build up over time but are not toxic. These will cause excessive algal growth, which is easily kept in check by regular water changes every 6 weeks to 2 months. 

Flow Rates

Flow rates can vary a great deal but a good rule of thumb to aim for with flow rates is a 200%, of your tank total capacity exchanged through your filter per hour. Strong flows associated with reef tanks are not appropriate for horses. 

Tank Furniture

Your seahorse will always need a hitching post. As you will see from some of our photos, we use marine grade rope. It has the advantage that it doesn't break down in salt water and is a brightly coloured background. As your seahorses will try to change colour to blend in with the background, the bright colours of marine rope will help your seahorse to retain its bright colours.

The heater that you use in your tank should be either set up to operate in a separate sump, or if it is positioned in the tank with your seahorse, you will need to cover it with a guard to keep your seahorse from grasping the heater with its tail and causing a burn.

Air Quality

Remember that anything you spray into the air in the room where your seahorse tank is positioned, will be immediately bubbled into the tank water along with your tank aeration. Many of these sprays, have the potential to harm your seahorse. These include insecticides, air fresheners, incense, hair spray and cigarette smoke. Its best not allow any of these substances in the room occupied by your seahorses.