Hello, Frank Indiviglio here. In 2001, I wrote a book about the Natural History and Care of Seahorses. As I intended, many readers were discouraged, due to the demands involved in their care and the fragile state of wild populations. Today, I am happy to report that captive-born individuals of several species are regularly available, and that the task of feeding them (a major stumbling block) has been greatly simplified. Still, they are not ideal for every aquarist. Following are some important points to consider before you decide to keep these intriguing but challenging fishes.
Seahorses Need a Wide Variety of Small, Live Foods
The world’s 130+ seahorse species (Family Syngnathidae) are strict live food specialists. Brine shrimp, the most easily-obtained seahorse food, is suitable as a steady diet for only one, the Dwarf Seahorse, Hippocampus zosterae (please see this article). Most others avidly consume brine shrimp, but will not survive long without amphipods (scuds, side-swimmers), sand hoppers, tiny shrimp, Mysids and similar marine creatures.
In recent years, captive-bred Big-Bellied, Northern, Yellow, Long-Snouted and other seahorses have been induced to accept frozen foods. Several breeders are now offering seahorses that are already acclimated to such diets (live foods remain an important supplement). Please see this website and post comments below if you would like further information.
Seahorses Cannot be Kept with other Fishes
Seahorses do well in pairs and groups, but, with few exceptions, fare poorly when housed with other marine fishes. Being slow, deliberate feeders, seahorses are inevitably outcompeted at feeding time. And, as live foods are relished by most aquarium fishes, it is difficult to selectively feed seahorses in community tanks. Pipefishes and sticklebacks (both seahorse relatives), and certain gobies will cause few problems, but most others should be avoided.
With attention to detail, however, a good many invertebrates may be maintained in the seahorse aquarium. Included among these are Banded Coral Shrimps, small hermit and spider crabs, sea stars, brittle stars, urchins, most snails, and tube worms. Please post below if you would like detailed information.
Wild-Caught Seahorses should be Avoided
Despite recent CITES listings and other protections, millions of seahorses are collected annually for use in Chinese and South Asian medicinal practices, and for the curio and pet trades. Others are threatened by habitat loss or perish as “by-catch” in commercial fishing operations.
Furthermore, wild-caught seahorses rarely adjust well to captive diets, and are often heavily parasitized. Please be sure to purchase only captive-bred seahorses.
Select Large or Dwarf Species
For most aquarists, seahorses on either end of the size spectrum are the best species with which to start. Larger species, such as the Atlantic Seahorse, Hippocampus erectus, and the Big-Bellied Seahorse, H. abdominalis, (please see articles below), will take a wider range of foods than most others. This allows us to provide them with the varied diet that is essential to long life. The Atlantic Seahorse, a particularly aggressive hunter, even consumes fresh-water creatures such as Black Mollie fry, fairy shrimp and blackworms. It also may accept frozen clams and prawn, and thrives at normal room temperatures.
The minute Dwarf Seahorse, H. zosterae, is the only species that fares well on a diet comprised solely of live brine shrimp. Brine shrimp intended as seahorse food should be fed finely ground fish flakes, spirulina tablets and similar foods for several days prior to use (please post below for details). Tiny marine invertebrates, easily collected via plankton net, should also be offered if possible.
Seahorses are Prone to an Unusual Malady
The seahorse keeper must understand marine water chemistry and be adept at diagnosing and treating fish diseases. However, even well-experienced aquarists are sometimes puzzled by an ailment unique to seahorses and their relatives – the accumulation of gas in the male’s pouch.
Treatment involves dispelling the gas via the careful insertion of a glass pipette, followed by medication with Methylene Blue or a similar anti-fungal preparation. Please see this article and post below if you need advice.
What’s Next: Learning More
First inspired by my grandfather’s efforts to breed seahorses in the 1960’s, I’ve written a number of articles and a book about these fantastic creatures. Husbandry difficulties and declining wild populations render it essential that we learn as much as we can about their habits and care. Please see the following articles and be sure to post your questions, thoughts and experiences below.
Hippocampus hippocampus image referenced from wikipedia and originally posted by Hans Hillewaert
Hippocampus bargibanti image referenced from wikipedia and originally posted by Steve Childs