Exactly how is the fluorescent protein gene added to the fish?
Every line of GloFish® fluorescent fish (i.e., GloFish® Starfire Red™ Zebra, GloFish® Electric Green™ Zebra, and GloFish® Sunburst Orange™ Zebra) starts with a single fish. The process, illustrated in this chart, begins by adding a fluorescence gene to the fish when it is a minutes-old embryo. 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.

Oh, joy…GMO pet fish…good luck on getting the goldfish instead!