SARASOTA, Fla. — Shawn Garner watches over 18 tanks of hundreds of tiny sea horses, bobbing among the artificial sea grasses and plastic zip ties provided to give their tails a hitching post.

“It’s the coolest animal in the world,” he said, showing them off with a touch of both pride and awe. “It has a head like a horse, a tail like a monkey and a pouch like a kangaroo.”

Garner, supervisor of the Mote Marine Laboratory’s sea-horse conservation lab, is one of several experts across the country trying to raise ornamental fish and other wild marine species in captivity. These researchers, many working at aquariums and zoos, are engaging in the kinds of farming operations once reserved for fish sold in food markets and restaurants.

For sea horses, the stakes are high. Nearly one-fourth of the 36 sea-horse species assessed by the International Union for Conservation of Nature are threatened with extinction.

Three factors account for the deaths of tens of millions of sea horses each year: the Chinese medicinal trade, accidental catch by shrimp trawling and other fishing operations, and habitat destruction.

“Being able to breed and raise sea horses is one part of the solution. Unfortunately, it’s not the only solution,” said Heather Koldewey, head of global conservation programs for the Zoological Society of London, adding that fishing restrictions and other coastal protections are also essential.

Before the 1990s, sea-horse farming was plagued by problems. Sea horses live in low densities in the wild — in many parts of the world, including the western Atlantic from Canada to South America and in Southeast Asia — so crowding them into a tank can stress them and lead to disease. Researchers in several countries — primarily the United Kingdom, the United States and Australia — have made strides in the past couple of decades, though reproducing the animals remains challenging.

The staff at the Birch Aquarium at the Scripps Institution of Oceanography in La Jolla, Calif., which has raised 12 sea-horse species, found that a tank usually used for jellyfish worked better than rectangular ones. The tank contains a slice of cylinder sandwiched between the two sides, and the baby sea horses were inside the cylinder, which kept them from getting trapped at the top edges because of poor water circulation.

“That really changed things for us,” said the aquarium’s co-curator Leslee Matsushige.

Mating habits

It probably doesn’t help captive breeders that sea horses — already unusual because the males carry the young and give birth — aren’t promiscuous and instead live in bonded pairs.

“They do flirt a lot, but they’re actually faithful,” said Koldewey, who also serves as field conservation manager for Project Seahorse. “There’s a lot of behavior to suggest otherwise, but if you do the genetic analysis, it’s just all show.”

Aquarists have also made some breakthroughs with sea dragons, which are related to sea horses but differ in several aspects, including the way they move and use their tail. There are just two species — leafy and weedy, named for their form of camouflage — and they live in the temperate waters off Australia. The Aquarium of the Pacific in Long Beach, Calif., became the world’s first to breed weedy sea dragons in 2001, from a progenitor named “Big Daddy,” but it only repeated that feat once, in 2003.