Genetically Modified GloFish®
GloFish® is a trademarked brand of genetically modified zebra danios, black widow tetras and tiger barbs, which artificially express various fluorescent genes from jellyfish, corals and anemones. Their colouration is a result of genetic modification, and not from dyes.
Genes are basically sequences of DNA that code for proteins (or polypeptides to be more exact). Genetic codes can be expressed by any organism, as long as they have the gene.
For example, the Green Fluorescent Protein (GFP) gene from jellyfish can be inserted into the DNA of the zebra danio. The genetically modified zebra danio now has the genetic sequence of GFP and will produce it, resulting in its neon glow.
The fish are reported to have reduced fertility, although some individuals are able to breed. The fluorescence gene can be passed from generation to generation, although intentional breeding to sell the fish is illegal as they are patented. The fish are bred and distributed by the company YorkTown Technologies.
GloFish® do not pose more environmental threat than their non-fluorescent counterparts. If released into the environment, they are unlikely to survive if the temperature is too low, or from predation. Their unnatural colourations and reduced fertility do not benefit their survival.
Notwithstanding, the intentional or accidental release of aquarium fish has ravaged some ecosystems.
Info: glofish.com; Image: M Bolt 2012, via Flickr