Tropical zebra fish have been infused with the gene of a sea anemone that makes them glow fluorescent red.
The GloFish are expected to hit the US pet market on January 5, but not if environmentalists opposed to transgenic species have their say.
The plans to market the world's first genetically engineered pet has touched off a debate over who should control the release of transgenic species.
The Texan company say zebra fish, with or without the red fluorescent gene, are safe and have been test subjects for decades in labs throughout the United States.
They point out that despite innumerable escapes from breeding pens and labs over the years, zebra fish accustomed to the balmy waters of their native India and Bangladesh have never established a wild colony in the nontropical waters of the United States.