a pet when it was introduced for sale in 2003. Research GM fish are widely used in basic research in genetics and development. Two species of fish- zebrafish and medaka, are most commonly modified, because they have optically clear chorions (membranes in the egg), rapidly develop, and the 1-cell embryo is easy to see and microinject with transgenic DNA. Zebrafish are model organisms for developmental processes, regeneration, genetics, behaviour, disease mechanisms, and toxicity testing. Their transparency allows researchers to observe developmental stages, intestinal functions, and tumour growth. The generation of transgenic protocols (whole organism, cell or tissue specific, tagged with reporter genes) has increased the level of information gained by studying these fish. Growth GM fish have been developed with promoters driving an over-production of "all fish" growth hormone for use in the aquaculture industry, to increase the speed of development and potentially reduce fishing pressure on wild stocks. This has resulted in dramatic growth enhancement in several species, including salmon, trout, and tilapia. AquaBounty Technologies have produced a salmon that can mature in half the time as wild salmon. The fish is an Atlantic salmon with a Chinook salmon (Oncorhynchus tshawytscha) gene inserted. This allows the fish to produce growth hormones all year round compared to the wild-type fish that produces the hormone for only part of the year. The fish also has a second gene inserted from the eel-like ocean pout that acts like an "on" switch for the hormone. Pout also have antifreeze proteins in their blood, which allow the GM salmon to survive near-freezing waters and continue their development. A wild-type salmon takes 24 to 30 months to reach market size (4–6 kg), whereas the producers of the GM salmon say that it requires only 18 months for the GM fish to reach that size. In November 2015, the FDA of the USA approved the AquAdvantage salmon for commercial production, sale, and consumption, the first non-plant GMO food to be commercialized. AquaBounty says that to prevent the genetically modified fish from inadvertently breeding with wild salmon, all of the fish will be female and reproductively sterile, although a small percentage of the females may remain fertile. Some opponents of the GM salmon have dubbed it the "Frankenfish". Insects Research In biological research, transgenic fruit flies (Drosophila melanogaster) are model organisms used to study the effects of genetic changes on development. Fruit flies are often preferred over