The two GloFish are very different, however, in what environmentalists and some experts say is a crucial way: The heat-loving zebra fish is from southern Asia and can’t survive long in cooler U.S. waters; thus, the Food and Drug Administration has ruled that there would be little threat of invasion of U.S. waterways if it were released from home aquariums. But the black tetra is native to South America and likely to be happy making a splash in the inland waterways of South Florida and Latin America.
In South Florida, the modified black tetras could upset an environment already burdened with 30 types of nonnative fish. In South America, they could mean an undesirable interference in natural biodiversity.
“My worry is that they’ll be such a novelty that they will be imported back to [South America] and kids will let them go and they’ll start interbreeding with fish whose genomes are very similar,’’ said Barry Chernoff, a freshwater fish biologist and chair of the environmental studies program at Wesleyan University in Middletown, Conn. “We would see the spreading of the fluorescent coral gene in the native fish.’’
Because pet fish are often let loose by owners who no longer want them, Chernoff and others say the threat is serious.
“The neotropical region contains the most diverse freshwater fish fauna and complex freshwater ecosystem in the world, with some 6,025 fish species so far recognized,’’ Gordon McGregor Reid, chair of the Wetlands International Freshwater Fish Specialist Group of the International Union for Conservation of Nature, said in an e-mail. “We meddle with this at our peril.”
Yorktown’s chief executive, Alan Blake, said the company chose the black tetra to modify because it is nonaggressive and shows no tendency to be invasive.
“The black tetra has been sold for over 60 years and there has never been an ecological concern with it,’’ Blake said.
There have been reports of natural black tetras in Florida’s waters. But Blake said there is no evidence that groups of them live there permanently; probably, he said, they are eaten by predators.
Blake pointed to research by Jeffrey Hill, who was part of the task force that reviewed Yorktown’s successful application to raise the GloFish tetra in Florida. In a 2011 study, Hill found that largemouth bass and mosquito fish in Florida ate twice as many red GloFish as regular zebra fish when they were all put in tanks together.
“Florida is a predator-rich environment. [The GloFish] is considerably more vulnerable’’ than its non-modified counterparts, said Hill, a nonnative fish specialist at the University of Florida’s Tropical Aquaculture Laboratory.