I have seen it done with mollies as well.
Ryan-- what are guppies famous for?-million fish, or they have a lot of baby guppies. Those baby guppies could survive and not die in a few hours in a tank, and then be food for saltwater fish.
Actually I had that Purple/yellow fish. He was a Royal Gramma. I named him "buddy". He was a very smart fish, that loved his cave.He was picture perfect and I had him for over 5 years. A nice $15 investment.