I am completely opposed to dying fish and can't imagine why anyone would do such a thing. I am also not too keen on creating a market for deformed fish like fish with no tails as such genetic deformities tend to come with other deformities internally (this tailless trait exists in all species of fish though it is usually culled - I had a tailless krib for awhile I felt sorry for).
But as I have said in other threads my blood parrots are in no way deformed, they are hardy and attentive and I like them. If you don't like hybrids you shouldn't eat any corn, peas, or in fact virtually any vegetable you can find in the marketplace. Same goes for many meat, dairy and fish products.