Who says GMOs can't be fun?!!!
The fluorescent color in our fish is produced by a fluorescent protein gene, which creates the beautiful fluorescence that can be seen when looking at the fish. The fluorescent protein genes occur naturally, and are derived from marine organisms. … Every line of GloFish® fluorescent fish (i.e. Starfire Red®, Electric Green®, Sunburst Orange®, and Cosmic Blue™) starts with a single fish. The general process of developing fluorescent fish … begins by adding a fluorescence gene to the fish before it hatches from its egg. Once the gene integrates into the genome (i.e., genetic code) of the embryo, the developing fish will be able to pass the fluorescence gene along to its offspring upon maturity. Because of this, the gene only needs to be added to one embryo; from that point forward, all subsequent fluorescent fish are the result of traditional breeding.
LINK: http://www.wired.com/geekdad/2011/08/genetically-modified-pets-your-kids-will-love/