I know Mats does't like these guys...
I'm not too keen on them either.
I think selective breeding for colour is just about OK, but messing around with a fishes basic body shape is unnecessary.
What happpens is these fish are heavily inbred to bring out these recessive traits. As a result they often suffer from reduced health and fitness, and therefore do not live for very long.
It's illegal for humans to do it, so why should it be OK to do it with animals?