The numerous books explaining how to equip a seawater aquarium may be used to keep seahorses. There is no need then to detail the subject.
One needs a 100 liters aquarium (about 25 gallons) at least to keep 2 to 4 animals, but this requires a careful maintenance. The seahorses measuring 20 cm (8 inches) or more require an aquarium of 200 liters (about 50 gallons) at least. Ideally a 300 liters tank (about 75 gallons) is recommended for 15 seahorses. A larger tank is not useful and could complicated feeding. Seahorses would find it difficult to feed themselves. The larger the tank the easier it is to maintain. The aquarium must be high and long (the width does not matter). On the other hand, it is necessary that your guests who belong to fragile sea species, should feel at ease and have an adequate equipping. Put some large clumps of "caulerpa" and other plants, they love to grasp them and to hide among the seeds. Living organisms in them are also recommended for life feeding. It is especially necessary to avoid any plant irritant or being able to capture and wound the seahorses. The day the plants produce oxygen (O2) and absorb carbon dioxide (CO2), but the night they absorb oxygen as the animals the PH drops. The setting should also include several other thin elements to allow seahorses to hang by the tail, i.e. dead coral, gorgonian, stones with slight cavities, "Aquaroche" (artificially manufactured stone), even plastic plants with thin stems (babies love them). Avoid any edged of sharp objects that may hurt the animals. A seahorse spends more of its time hanging or fixed to something suitable. You may even prepare small shelters. "Alive stones" can be welcome but are not compulsory as they may often be dangerous.A quarantine period is strongly recommended. Seahorses enjoy to nose around in search of their food, have a good appetite and stones may stimulate their curiosity. But as it has been mentioned by some specialists you never know what organisms live in these stones we put in our tanks. Some of them may be dangerous and lethal, for instance crabs, leeches, fireworm, hydroids, aiptaisias... Attention, the crab and other shellfish are the largest enemy of the seahorses. At sea it's also a penguin: l'Eudyptula minor and the fish: Antennarius striatus for instance. One has to be day and night watchful when it comes to keeping seahorses because of their specific behavior. One should never use metal elements. You should favor plastic or natural elements provided by the sea. Your imagination will cope for the rest. Avoid hanging up a seahorses aquarium to a reef aquarium, thinking that this would be a convenient solution. An aquarium of seahorses has to remain a secluded place.
For water filtering you should use the best device in order to provide a high quality water : seahorses are sensitive to any change of water parameters. Do not use over powered pumps as seahorses dislike violent streams. A 600 to 800 liters/per hour water flow (about 150 to 200 gallons) is enough for a 100 liters tank (about 25 gallons) : i.e. a water circulation of 6 to 8 times the water capacity is enough. Watch out : a pump linked to long pipes provides a lower flow than indicated by the manufacturer. Aim the pump and filter streams so as to insure a quiet tank. When a seahorse enjoys going into the stream, it will choose to do it. However use a good quality and quantity of filtration material, for instance pre-filter, carbon (if regularly renewed, once a week), one or several biological filters (according to the quantity width and length). Mind you, an important filtration capacity is never to be considered as harmful, on the contrary. There are various systems of filtraton (for example decantation filter internal or external, filter under sand, external sand filter, external filter dry/wet...).The DSB (Deep Sand Bed = alive sand) associated with alive stones seems to be a fashionable filtering method, but as the alive stones in the ignorance of what kind of living organisms may be introduced into the sand. I oppose such handling ! The Jaubert method is also to be excluded.
A scum device may be useful but not necessary, if tank maintenance is regularly done. It is particularly useful after medical treatment , anyhow this device is to be used occasionally to avoid a possible culture medium in the event of declared disease. An UV-sterilizer is firmly recommended to prevent diseases. For an aquarium of 100 liters (about 25 gallons), lighting should be at least 36 watt, viz two neons of 18 watt and have a 100 Watt heater. Lighting 8 hours at 10 hours during the day, it is necessary to respect the cycle of the sun because certain ritual such as the birth happen early the morning.
Wait 2 - 3 months so that the aquarium is well prepared and that the bacterial flora has stabilized.
There are diverging opinions as to the use of air diffusers. These are compulsory when a tank is short of oxygen, resulting in death of all living creatures, especially in presence of high temperature (in Summer for instance). They may however be harmful as it is true that seahorses may swallow the air either for fun or to get rid of parasites. They may die due to large consumption of air. I seldom had seahorses who having the bad idea of swallowing too much air due to bacteria or parasite problems, which provoked "bubbles" on the tail and led sometimes to death trough embolism. As a rule this happens only when something goes wrong. It is then necessary to look for the main reason of the event. Seahorses, whether adults or babies, are normally clever and have the reflex to avoid keeping their heads under the air, because they like to stay around for a short time . Air diffusers are moreover an excellent way to detect a disease. It is important not to place the diffusers under the gravel, as seahorses may confuse the large bubbles with some food.
It is also important to check that the small bubbles come up in a straight line and do not diffuse in the tank giving the water the aspect of a cloud. The best way is to put them vertically on the top of the tank bottom, so that only small bubbles pop out. It is recommended to put them away of the current caused by the filters and pumps. It must be pointed out that this oxygenation system is not the best as it sends the ambient air into the tank, around 21 % of oxygen (O2) and 79 % of nitrogen (NH2). One has then to use large air flow pumps.
There are more performing oxygenation systems. Personally, I have never met any problems with simple systems. A good aeration favors the transformation of the toxic elements (NH3-->NH4-->NO2-->NO3). Other parameters of the water will be supported hardness, PH etc.
Certain types of filters, such as the systems dry/wet or semi-wet, contribute to oxygenation of the aquarium. The plants support also oxygenation during the day.
Water parmeters and Maintenance
For tropical species, salt density nearing 1021 is suitable (30-33 g/l). Do not exceed 1023 up and 1020 down (in presence of disease). Salt density should be checked from time to time. As for other parameters avoid brutal and important variations. This could disorganize the seahorses immune system and lead to disease. Add water progressively if salt density is too high, or sea salt if needed. Seahorses enjoy a water temperature at least of 26 degrees Celsius (around 78,8 Fahrenheit). The minimum supported is 24 degrees Celsius (around 75,2 Fahrenheit), at least do not exceed 30 degrees Celsius in Summer (around 86,0 Fahrenheit). Any brutal variation is to be avoided. Also avoid or eliminate tank pollution or changes in the parameters (ph, hardness, and so on).
For subtropical species, keep a salt density around 1021-1025 and a temperature of 22 degrees Celsius (around 71,6 Fahrenheit), do not exceed 25 degrees Celsius (around 77,0 Fahrenheit).
For temperate water species, salt density is around 1027, and the temperature of 19 degrees Celsius (around 66,2 Fahrenheit), do not exceed 22 degrees Celsius (around 71,6 Fahrenheit).
Any aquarium pollution or change in parameters (PH, alkalinity (8,2 - 8,4) - TCHA or KH (8,0) - etc. should be foreseen and if present must be eliminated. The maximum rates of ammoniac (NH3), ammonium (NH4), nitrites (NO2) nitrates (NO3) and phosphates (PO4) tolerated by the fish are unsuitable for seahorses. The best thing to do is to keep quality water (0 mg/liter - ammoniac (NH3), ammonium (NH4), nitrites (NO2), phosphates (PO4) < à 0,5 mg/liter), by regular water changes. (You can maintain a low nitrates (NO3) level, the least dangerous element, to preserve the plants that feed on it otherwise they will decay).
A 10 % weekly water change is recommended for a normally populated tank. For large tanks a renewal every 15 of even 30 days is certainly enough.
If needed, you may change the water more often, but wait a two to four days between each change. This will not harm the seahorses, if you are careful. In case of emergency avoid a water change exceeding 50 % of the tank capacity in one time. However in case of need a 100 % change is better than a sick tank. Take care not to disturb the nitrification cycle by adding the necessary purifying bacteria.
Whatever the amount of water you need to change you should store the sea water 24 hours in advance in a neutral plastic or glass container only used for that purpose. Use only cool water (never use warm water) and high quality sea salt found in specialized shops.
In order to get the required water (without chlorine, lead, or other harmful matter) add a water conditioner. If your water is not suitable ((hardness, PH 8,2-8,4, magnesium, calcium etc.) use a device to condition the water or osmosed water sold by specialists. Bring the prepared sea water to the temperature and density of the tank.The frequency and cleaning rules are the same as for coral tanks (pré-filter once a week, filters 1/3 of the filter mass once a month, carbon renewal once a week; it is to be noted that a saturated carbon suddenly rejects the toxic substances in the aquarium). It is aslo necessary to clean 1/4 of the sand once a month or to try to introduce snails as the strombus which eat the sediments.
Appearance or proliferation of unwanted algae (green = are not dangerous but unpleasant and unattractive, red, brown and blue = being dangerous) is due to a state of imbalance in your aquarium. You must immediately eliminate these algae, because if they grow too much they release substances in the water and reduce the health of aquariums. The same caution is to observe for superior plants and algae, they should not colonize an aquarium.
Several factors are responsible, here are the principal ones :
Always keep an eye on the water chemical properties. A healthy tank today may easily become tomorrow a sick one. Remember : it is better to be watchful than to remove dead animals. The real puzzle for a seahorses keeper is treating and healing these creatures.
- Too much or not enough light (adapt the time or power of lighting);
- Unsufficient oxygenation (check the level of oxygen in your aquarium);
- Water pollution, PH, KH or other destabilizing factors (check all the parameters of your water and proceed to frequent water changes - manually tear off the undesirable algae - brush the decoration);
- Bad mixing or circulation of water, by under-sized or inadequate pumps and filters (check again the installation);
- Badly planned installation (check the whole installation);
- Non-compliance of the tap water or presence of silicium (in such a case use osmosed water);
- Too much waste or overpopulation ((lack of maintenance).