Glow In The Dark Fish

About Transgenic Glow Fish

Danio fish in aquarium.
artas / Getty Images

In 2003 glow fish, created from Zebra Danios, joined the ranks of altered or man-made aquarium fish. Just like the painted, dyed, and man-made hybrid fish before them, they quickly became popular among consumers eager for something new and different. The glow fish's bright colors made them instant best sellers. While they don't actually glow in the dark, their bright colors do fluoresce under blue light and make them quite colorful, just like saltwater reef fish.
Now, besides zebra danios (Danio rerio), there are tiger barbs (Puntigrus tetrazona) and tetras (Gymnocorymbus ternetzi) that have been genetically modified to carry the bright color genes. Taiwan's Council of Agriculture revealed that it has also successfully produced transgenic convict cichlids (Amatitlania nigrofasciata) and angelfish (Pterophyllum scalare).

How It Started

It started off innocently enough when a professor at National Taiwan University extracted a fluorescent protein from a jellyfish and inserted it into the genome of a zebrafish egg. He was hoping to make the organs of the zebrafish easier to see when he studied them, but to his amazement, the entire fish began glowing under blue lighting.

Later he presented a slide of his glowing fish at a conference, where it captured the interest of a tropical fish production company. Seeing its value in the tropical fish retail market, they agreed to fund the professor’s experiments in exchange for use of his techniques. Using different colored jellyfish proteins allowed new colors to be produced. The rest, as they say, is history.

The glowing fish, named TK-1 by its creator, soon was being sold in the Asian market. By late 2003, sales had expanded to the United States. Not everyone was in favor of marketing the fish, and considerable debate is raging over the ethics and safety of marketing genetically altered fish. But a new species of glow fish and colors are being developed and the demand for the fish by aquarists is growing.

Sales Ban

The FDA has stated that the genetically engineered fish are no more threat to the environment than unaltered fish, and therefore do not warrant regulation. California wasn't about to let the matter pass, and promptly chose to block sales of glow fish. The regulations were lifted in 2015 due to the findings of the Food and Drug Administration and the Florida Department of Agriculture and Consumer Services that the fish posed no environmental risk. GloFish are now legal in California for importation and commercial sale. Canada, Australia, and Europe also had originally banned the fish, but now they are available for sale.

The primary arguments against the fish are environmental and ethical concerns. There was fear that if genetically altered fish were released into local waterways they could harm the environment, or animals might consume them and suffer side effects. Many feel that selling genetic alerted fish is not only ethically wrong, but it sends the wrong message to children. Others feel that any alteration of a living creature is an abuse of the power we have over life and consider it nothing short of biological pollution. Still others express concerns that if glowing fish becomes popular, what will be next - glow in the dark cats and dogs? Where will the line be drawn?


Meanwhile, proponents say the fish is completely safe and is an attractive alternative to keeping colorful, but more expensive and difficult to care for, saltwater fish. They cite reports showing that if glow fish were to find themselves in natural waters they would be unable to survive. The bright colors of the glow fish will actually make them easy prey in the wild if they do get out into natural waterways.

The other advantage of glow fish over other forms of colored fish is that the glow fish is created in the egg and the fish that hatch will reproduce naturally and pass the glow coloring on to their offspring. The dyed, painted, injected or otherwise artificially colored fish that are sometimes available in fish stores are actually harmed in the coloring process, the colors are not permanent and will gradually fade, and the colors to do not pass on to the offspring.

Article Sources
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  1. Statement Regarding Glofish. U.S. Food and Drug Administration.

  2. Sales of Glofish in California. State of California Department of Fish and Wildlife.

  3. Environmental and Indirect Human Health Risk Assessment of Glofish Cosmic Blue and Galactic Purple Danios: Transgenic Ornamental Fish. Canadian Science Advisory Advisory Report.