One newly bioengineered salmon, endowed with a gene from an eel-like fish, grows five times faster than its natural cousins. Another genetically modified salmon produces antifreeze in its blood so it can survive icy waters that swirl through oceanic fish farms.
A tropical zebra fish, infused with the green fluorescent gene of a jellyfish, glows in the dark -- a living novelty that promoters hope will be a must-have for the home aquarium.
These experimental superfish are more than laboratory curiosities. They are the progeny of genetic engineers whose skill at mixing and matching genes is outpacing laws and regulations meant to protect the food supply and the environment.
None of these designer fish, being pushed by biotech entrepreneurs as potential lucrative ventures, have yet reached the market. But the U.S. Food and Drug Administration has initiated a review of the souped-up salmon, a process that could lead to the first approval of a "transgenic" animal -- one that has genetic material transplanted from another.
Although the human health implications of eating bioengineered animals remain unknown, a panel of scientists last August reported it had "a moderate level of concern" that new species could trigger allergic reactions. What might happen, the scientists asked, if a gene from a shellfish were implanted into a fish? Could it cause a reaction in consumers hypersensitive to shellfish?
The National Academy of Sciences panel, assembled at the FDA's request, said its primary concern was the potential for ecological havoc should highly mobile, fast-breeding transgenic species escape into the wild.
"It is possible," the panel reported, "that if transgenic salmon with genes engineered to accelerate growth were released into the natural environment, they could compete more successfully for food and mates than wild salmon."
That means these "Frankenfish," as critics have labeled them, could squeeze out their wild cousins, driving them to extinction through interbreeding or by eating them.
Alarmed by the potential risks, Washington, Oregon and Maryland have banned genetically enhanced fish to protect the native fish populations.
California's Fish and Game Commission, trying not to hinder scientific research or the state's burgeoning biotech industry, plans to grant permits, based on its own reviews, for each new transgenic species as it emerges under new rules that take effect today.
"We could have put up a stop sign and said, 'No,' " said Michael Flores, president of the Fish and Game Commission. "But then we would have crippled our university researchers and other research and development. We will look at every single species and make sure safeguards are in place."
West Coast commercial fishermen are pushing California to ban genetically altered fish, arguing that the potential threat to wild salmon and other native species is too great.
"Once this genie escapes, can we put it back in the bottle?" asked Zeke Grader, executive director of the Pacific Coast Federation of Fishermen's Assns. "I doubt it.
"So what happens when these fish get out in the wild? Will they spread disease? Will they be predators of our native fish or interbreed with them? How can we assure the public the fish we catch are safe if transgenic fish are mixed in?
"It's all unknown," Grader said.
It's the FDA's job to answer those questions. But "marine ecology is not historically an area of FDA scientific strength," said Michael Taylor, a National Academy of Sciences panel member and senior fellow at the nonprofit Resources for the Future.
Taylor and others also fault the agency for closing its reviews to the public to protect trade secrets.
Lester M. Crawford, deputy FDA commissioner, said the agency is reconsidering its secrecy policy when weighing the food safety and ecological impact of newly designed species.
"We certainly have a framework to deal with environmental risks," Crawford said.
But new breeds of transgenic animals have prompted some internal soul-searching. "We are evaluating whether we need new regulations or new money or congressional authority to tweak the law," Crawford said.
He said the agency may never approve a transgenic fish or any other kind of genetically modified animal for the marketplace. But the pressure is mounting to do so, with a menagerie of them expected to arrive at the FDA's offices soon.
Researchers at biotech companies and universities have redesigned the genes of freshwater catfish and tilapia to make them grow faster, and those of shrimp and abalone to help them resist disease.
Scientists in Singapore are designing ornamental fish -- such as the zebra fish -- that glow green when spliced with a jellyfish gene or red when infused with the gene of a sea anemone.
Those same researchers are devising a fish that changes color when it passes through different temperatures. Such gene-splicing is being extended to goldfish and koi, stirring excitement in the $1-billion annual home aquarium trade.