For Marine Aquarium Cultured Fishes and Invertebrates
© Dr. Amanda VincentUniversity of Oxford, England
Article by Dr. Amanda Vincent , Copyright 1995. Reproduced by permission.
(This article first appeared in Volume 3 Number 1, The Journal of MaquaCulture <../../newslttr Winter 1995.)

WEB Editors note: Dr. Vincent has granted permission for this reproduction with two conditions. 1. A reminder that this was generated from her “ROUGH NOTES” 2. These articles may be updated by Dr. Vincent or Dr. Heather Hall, at their discression. Editor’s note: Dr. Vincent kindly allowed Joyce Wilkerson to use excerpts from her “rough notes” for this article. This article is not to be reproduced without the permission of Dr. Amanda Vincent, Darwin Research Fellow, University of Oxford, Department of Zoology, South Parks Road, Oxford, OX1 3PS.

Seahorse keeping should not be tackled by the casual aquarist, because seahorses usually die quickly in captivity. Seahorses are already at risk around the world, partly because they are exploited for aquarium fishes. The following notes are intended only for very experienced marine aquarists. Think about whether you can realistically hope to care for these fishes, before you buy them, and if you have any doubts, choose something easier.
The Seahorse
Seahorses are in the same family as pipefishes and seadragons (Syngnathidae). There are probably about 35 seahorse species in the world, all in the genus Hippocampus, ranging in adult size from the 40 cm Eastern Pacific seahorse (H. ingens) to the 1.5 cm New Caledonia seahorse (H. bargibanti). Seahorses usually cling to vegetation or other holdfasts such as sponges, pilings or ropes on the bottom, sometimes in less than one meter of water and often only meters from shores. Crabs occasionally prey on seahorses. Seahorses can change colors often and easily. Do not distinguish between seahorses by color. The head coronet shape and size vary greatly from seahorse to seahorse and are an excellent way of identifying seahorses individually.
New Seahorses
Choose your seahorses with great care. If they have grey tinges or signs of fungus or sloughing skin, do not buy them. It is difficult to impossible to treat most seahorse illnesses. Seahorses in good condition have rounded bodies. If the body is sunken and concave it is probably best not to buy the animal, as it has obviously not been properly cared for and will almost certainly succumb to illness. Seahorses are very vulnerable to bacterial infections so place new seahorses in a separate tank which has been treated with a wide-spectrum antibiotic or dip them in a bath. To acclimate seahorses, the unopened plastic bag should be placed in the aquarium for about half an hour to allow water temperatures to equalize. Then gradually, over the next hour, add aquarium water to the bag. Once the bag is more than half full of aquarium water, you can risk adding the seahorse to the tank.
To encourage a seahorse to release a holdfast, move the holdfast gently. If that fails, then tickle its tail. As a last resort, try to uncurl the tall gently from the perch. Never use force to get a seahorse to release a holdfast. You will do great damage to its tail. Just wait and try again.

Seahorses are oriented vertically and are not suited to shallow aquaria (<45 cm). They are unlikely to mate in shallow water because they rise as they copulate. However, they often move across thetank bottom so give them as much space as possible. You should not keep many seahorses together. They do not live in groups in the wild and they are very prone to communicable diseases and ailments. I suggest no more than four seahorses in a 100 liter aquarium and not keeping any seahorses in much smaller tanks. An ultraviolet sterilizer is an important because seahorses are very vulnerable to bacterial infections. It’s a good idea to hide airstones. Seahorses are subject to many buoyancy problems that may result from or be exaggerated by sitting in airstone bubbles. Water quality is all-important for maintaining seahorse health.
Aquarium Settings
Seahorses require many holdfasts, as they become stressed if they cannot hold onto something with their tails. The best holdfasts are natural surfaces such as “living rocks.” Excellent substitutesare soft plastic plants. They should be quite tall and have many branching parts. It is also important to provide a reasonably complex environment so the seahorses can escape into hidden corners. They become stressed it they are too exposed. It’s also a good idea to have a tank backing to givethem a reference point and to help them orientate.
It’s very important not to put seahorses in an aquarium with fast, agile fishes or with aggressivefeeders. They tend to do best in invertebrate aquaria but otherwise they can be kept with dragonettes (Callionymus bairdi), tiny trunk fishes (Lactophrys trigonus), small pipefishes (although it has been suggested that these may become ‘fin pickers’; as they grow), blennies, etc. Never place seahorses with active feeders such as damselfish, puffers, butterfly fish or angelfish. Blennies inparticular make quite good companions because they help to keep the tank clean. Be careful that the companions aren’t too large: one of my blennies which had grown large suddenly attacked all the seahorses in its aquarium one day, killing a number of them.
Seahorses interact most in the hours just after dawn. I suggest, therefore, that you keep seahorses on 3 hours half-light / 10 hours light / 3 hours half-light / 8 hours dark. The half-light can be produced by a lamp some distance from the aquarium.
Seahorses eat a great deal but are rather particular. Feeding seahorses is one of the most difficult aspects of keeping them in captivity. Seahorses usually eat only live, fresh food. They need food variety and cannot be fed solely on Artemia as these alone provide a highly unbalanced diet. With patience and effort, you may convince seahorses to eat some frozen foods and these can be a good backup when fresh food fails. However, you must not rely solely on frozen foods as these alone will eventually result in malnutrition and illness.

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