the only class of animals that has no worries when it comes to inbreeding are reptiles. Yes you may not have strong genes and the odd deformity and weak immune system but they will normally die and only the strong survive. They're not mutants, just different. Its called evolution. You might just breed a superfish that will wipe out all humankind. Or some freakish hideous novelty creature that someone will pay crp lds for. Where did the sicko goldfish with the bubbles below their eyes come from. Or the lionhead goldfish with the humungeous melon heads. Or a balloon molly. I saw one today at the LFS and it looked like it had swallowed a rather large marble. A ball with fins. And i nearly bought some. The world would be indeed boring if nothing ever changed, have a look at some origonal wild specimens of the fish we keep. Some you wouldnt use for bait. Yet their distant cousins are sought after for their colours. Seen a wild guppy? not that colourful. cause they get eaten if their seen. so who did we keep and breed. the freaky mutants