AUSTIN, Texas, Dec. 30 -- The GloFish, the in-demand fluorescent zebra fish that's being called the first gentically engineered pet, was originally bred to help detect contaminated waterways, said its developer, Yorktown Technologies. The scientists wound up with "a breakthrough in the ornamental fish industry," said Alan Blake, president of Yorktown Technologies, in a recent Associated Press (AP) article. "The first step in developing these pollution-detecting fish was to create fish that would be fluorescent all the time. It was only recently that scientists realized the public's interest in sharing the benefits of this research," Blake told the AP. To create the fish, researchers at National University of Singapore spliced a sea anemone gene into what nature intended as a black-and-silver zebra fish, a species common in aquariums around the world. They made a freshwater fish with the bright red color of a tropical saltwater reef dweller. Fluorescent fish absorb light and then re-emit it. This creates the perception that they are glowing, particularly when an ultraviolet or black light is shined on the fish in a dark room. Yorktown Technologies, which provides detailed scientific information about GloFish on its Web site, said, "Fluorescent zebra fish have been relied upon by scientists worldwide to better understand important questions in genetics, molecular biology and vertebrate development for over a decade. Fluorescent zebra fish have been particularly helpful in understanding cellular disease and development, as well as cancer and gene therapy." The company said scientists are in the process of adding a "switch" that will cause the always fluorescing zebra fish to selectively fluoresce in the presence of environmental toxins. A nonfluorescing fish will signal that the water is safe, while a fluorescing fish will signal trouble. Yorktown said public demand for GloFish has been "extraordinary." Distributors 5-D Tropical and Segrest Farms have already begun shipping limited numbers of the fish to some stores, and they will be available nationwide on Jan. 5 -- except in California, where regulators have banned most uses of such transgenic species for fear they could spread into the wild and harm native populations. A portion of the proceeds from sales of GloFish will go to the lab where they were created, the company said. For more information, visit: www.glofish.com/science.asp