inbreeding is never a good thing for any creature. the offspring will be weaker and more disease prone. also, any genetic disabilities (or whatever it'd be called) which the father had and then passed onto his daughter would only be accentuated in the offspring of that father and daughter.
Not nessiserily, no matter how nice a fish, they can all carry problems in their genetic code. Breeding two blood relatives together will result in a much much higher chance of a problem occuring, like a genetically inherited disease (if fish can get them that is).
I would not advise it.
Well they do it with livebearers to create a quality fish. But cichlids are another thing. If a human bred with his sister, the baby would have to be put down, but with cichlids. Im not sure. Im sure it happens all the time from not being seprated.
I might try it with my convivts. But never fear as the babys wind up as food for my angels anyway.
as long as they look fine, no abnormality's then their offspring should be fine. i'm breeding rams and they are brother and sister but i picket the best male and female and sold the rest