GloFish Zebrafish (Danio rerio), red and blue versions. Although not originally developed for the ornamental fish trade, it is one of the first genetically modified animals to become publicly available. These fluorescent fishes were developed with a gene that encodes the green fluorescent protein from a jellyfish. The gene was inserted into a zebrafish embryo, allowing it to integrate into the zebrafish's genome, which caused the fish to be brightly fluorescent under both natural white light and ultraviolet light. Their goal was to develop a fish that could detect pollution by selectively fluorescing in the presence of environmental toxins. USA