TAIPEI, Taiwan -- In the basement of a building down an alley here floats the future of bioengineered pets, and it is glowing.

In a corner, small fish flit about in a dozen aquariums. Bill Kuo, a manager at Taikong Corp., draws a thick curtain and switches on black lights over the tanks. Suddenly, the fish glow a bright green. "Imagine you come home from work, turn out the lights and look at these," Mr. Kuo says. "It's very relaxing."

Fluorescent fish are just one of the latest off-the-wall innovations to come along in the biotechnology march. American researchers are seeking approval for a super-size salmon, retooled with growth hormones. A Canadian company, Nexia Biotechnologies Inc., is injecting spider genes into goats to produce milk that can be refined and woven into "BioSteel," for use in surgical sutures and "ballistic protection," the company says. Another Canadian group has trademarked the name "EnviroPig" for its genetically modified swine, whose manure contains fewer phosphates, a natural pollutant.

But Taikong's fish, which hit the market in Taiwan last month, may well be the world's first genetically modified house pets -- certainly the first designed to glow in the dark and one of the first leisure-time applications for genetic engineering. Born in a Taiwan biologist's lab in 2001 and written up in a scientific journal, the fish were soon discovered by Taikong, a 20-year-old company that sells aquarium equipment and fish food to shops around the world.

Willis Fang, Taikong's president, thought the appeal of the little green fish might go beyond research. He made plans to bring them to market as "Night Pearls," along with a whole line of products for the fish, such as black-lit tanks, fluorescent plastic coral and "fluorescent fish pellets" for food.

Okay, so, yeah, cool fish and all, but man, check out that paragraph about crossing sheep with spiders. Finally, the sci-fi age is coming our way. Can't wait for the teleporters and ray guns.