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Who's afraid of monster fish?

With time, fish and wildlife experts have outgrown their fear of the walking catfish.

FORT LAUDERDALE - The walking catfish sent unsettling ripples through Florida after surfacing on a north Broward County angler's hook in 1967.

The discovery of that exotic fish, capable of undulating briefly over land with its stiffened pectoral fins and a body-rocking motion, spurred projections that the species would dominate, and perhaps seriously harm, native Florida fish populations.

That Frankenfish fear has yet to pan out, said Paul Shafland, director of the Florida Fish and Wildlife Conservation Commission's Non-Native Fish Research Lab in Boca Raton.

"It's certainly not had any of the catastrophic effects originally associated with its find in Florida," he said. "However we still consider it problematic. We wish it weren't here."

The walking catfish, Clarias batrachus , breathes air and can make short migrations across land, which it sometimes does after rains leave standing water and soggy landscapes. While other exotic fish live subsurface lives, the south Asian native's land locomotion brought it headlines.

"People saw a fish out of water, and it just had a lot of sensationalism attached to it," Shafland said.

The catfish covered a lot of ground rather quickly once it got a foothold outdoors. It has spread, via interconnecting canals and other means, from the first catch west of Deerfield Beach north to Walt Disney Co.'s Magic Kingdom, where a worker recently snagged one, said Walt Courtenay, fisheries research biologists for the U.S. Geological Survey.

One of 34 exotic fish existing in Florida, the walking catfish remains widespread and "locally abundant," Shafland said. It fanned out across 20 counties in just 10 years, according to the Florida Museum of Natural History.

But scientists said its numbers appear to have declined in the 1980s and 1990s after an initial population boom.

"We've seen that with a lot of introduced fishes," said Bill Loftus, a Geological Survey research ecologist based at Everglades National Park. Predators eventually start to hunt them, food dwindles and their proliferation is curbed, he said.

"They don't really crash - they come to a kind of balance with the environment," Loftus said.

The lack of a visibly serious impact from walking catfish does suggest that "the aquatic ecosystem is far more resilient to disturbances than what is commonly perceived by environmentalists," Shafland said.

A 1970 Smithsonian Contributions to Zoology article described the walking catfish's foray into Florida as possibly "the most harmful introduction to any North American area so far witnessed," Shafland noted.

Shafland thinks the thus-far innocuous fate of the walking catfish should temper fear generated by more recent exotic fish finds in South Florida: the discovery of the Asian swamp eel on the county line between Broward and Miami-Dade in 1998, and the bullseye snakehead in Sunrise in 2000.

Still, in aquatic environs, "Once an exotic species becomes established, it's impossible to eliminate," Shafland said.

The walking catfish dominates isolated pools of water in marshes and culverts and certain types of ditches, scientists said. It lives and reproduces in the Everglades.

While not notably detrimental in nature, the walking catfish has meddled seriously with the business that accidentally introduced it to wild Florida: aquaculture.

The species has made raids on the ponds of fish farmers, where "they'll eat all their crops," Shafland said.

Fish farm owners have responded by building levees and fences to keep them out.

"The single biggest problem is with them crawling into aquaculture ponds," Shafland said.

[Last modified January 17, 2005, 01:05:20]