Scientists are working to improve the drastic decline in the numbers of the Devil's Hole pupfish, an endangered species of tiny size -- almost as difficult to see in the water as the odds are long the fish will make a comeback any time soon.

After a disastrous flood last winter that left only 38 pupfish, according to a survey count this past spring, resource managers decided to farm out the pupfish. They found foster homes for the survivors at Shark Reef at Mandalay Bay in Las Vegas and at Willow Beach National Fish Hatchery in Arizona.

As of April, a total of 67 of the Devil's Hole species of pupfish (Cyprinodon diabolis) were known to exist in the world. Listed as endangered since 1967, the species is native only to Nevada.

About half the fish were located in a concrete pool refuge near Hoover Dam. But according to the new management plan worked out by biologists and regional managers of the National Park Service and the U.S. Fish & Wildlife Service, all the refuge pupfish except for two males are to be consolidated at Willow Beach National Fish Hatchery, where work has commenced to propagate and rear the fish.

Fish & Wildlife Service officials hope that the new refuge will stabilize the pupfish populations and lead to their recovery.

The two male pupfish will remain lodged at Shark Reef at Mandalay Bay, where biologists plan to use experimental techniques with hybridized female pupfish, based on fish populations current at Devil's Hole, to get the fish to reproduce.

Biologists hope the fish offspring will genetically resemble pure-bred Devil's Hole pupfish.

"Reversing the decline of the pupfish is difficult and compounded by the low numbers of reproducing adults, their short life span and the difficulty of propagating them in captivity," said Bob Williams, field supervisor with the Fish and Wildlife Service in a statement. "It's incumbent upon us to make every effort possible to maintain this species."

Since the April count of pupfish at Devil's Hole, emphasis has been placed on trying to understand how to propagate the pupfish outside of their natural habitat at Devil's Hole, a dark cave housing a spring-fed seep that remains at a constant year-round warm temperature.

Hybridized female pupfish were moved in May from the Hoover Dam refuge to mate with two male, wild pupfish from Devil's Hole. The females successfully spawned, but the eggs were not viable.

In July and August two more Devil's Hole males were removed to the refuge at Mandalay Bay, along with a female from the Hoover Dam refuge.

Last week the remaining pupfish at the Hoover Dam refuge had to be removed because it became infested with invasive snails, which eat baby pupfish like they're going out of style, which they are.

A Mexican pupfish expert, Dr. Arcadio Valdes, a biologist from Monterrey, Mex., has successfully developed techniques for hatching pupfish eggs in aquaria in Mexico and is currently working with hatchery staff at Willow Beach.

The hope now is to develop dieting and breeding techniques that will allow the pupfish larvae to mature into juvenile and adult pupfish in an environment free of predators.

Another survey will be conducted at the end of the month at Devil's Hole to determine how many wild pupfish are left, Williams said.

"It's a multi-pronged approach," he explained of the service's plan. "It depends on the number of fish found in Devil's Hole; if it's a small number, we may have to rely on other techniques" than simply working to keep the wild pupfish alive.