IMO there's nothing wrong with them besides the danger of them getting into the wild (though they would probably not survive - having those colors - to reproduce). It isn't cruel, the color passes on naturaly and, although it's a little annoying that these people are now benefiting from exploiting these fish, I don't see a difference between marketing these and any other man-made (ie selectively bred) strain of discus or guppy or danio or whatever. They've also done something similar with rabbits - and I'm sure several other species besides.