A few people breed brother and sisters to form a pure colour/strain/line as when people crossbreed fish to make pretty fish for their own pleasure. then spread them around and we get weak fish.
then very experienced breeders need to get the back to the pure colour because we have run out of pure one and we are just left with mixes.
one breeder might have on batch of fry which are very close to the pure colour so you pick the best ones from that lot then breed them, then pick the best lot from the fry, then breed them etc.......
Which is very time consuming and not easy to do.
Hope that makes sence :lol: