They are the brain child of a BRILLIANT research team. They needed a way to fund transgenic research and decided to try something nifty that could be made available to the public at a price the public could afford and they could still profit from. But it had to be eye catching... how about small, hardy, easily cared for fish that glow.... yeah that will work!
Every glo fish bought is helping to fund transgenic research. Its the single most succssfun fundraiser for scientific purposes I have ever encountered. There are now a few companies that are simply making profits selling them, but originally they were for funding transgenic research.
The ones you buy aren't sterilized. But breeding them will put you in violation of some proprietary license agreement and is actually punishable in a court of law. I suppose first they have to catch you breeding them.