I agree- putting this perception on fish made me think it was horrible at first too.. But I guess fish are just different, as I'm sure are insects, crustaceans, stuff like that.
I watched a show where a lady was breeding her champ. mastiff (like top in America) to his daughter, and she went through soo many tests and precautions about it. I was kinda grossed out haha.
Anyways, very off topic, but not in a sense. That guy will have very little progress if he never inbreeds fish, I believe. Not that he knows what progress is.