Hmmm my apologies to all, I think the info I gave was on fluoresceing danios, which are (I *think*) not yet on the market, or not to the extent of these zebrafish. If these fish were intended for release into the waterways by scientists, they must (I hope) be relatively sure they will cause minimal impact on the environment. Of course things could easily still go wrong, but it's something I guess. I still disagree with this type of cross breeding, because it's unnatural, and as TorPeteO said, the animal testing (torture) involved in getting these guys to the stage where they can be released for a (potentially) useful purpose would be taking thousands of poor fishy lives in a very cruel way. I vote we cut down on pollution so there's no need for these fish in the first place.
Dan - sorry mate, I wasn't picking on you, I agree that some animals are probably destined to die out, but hundreds of species are going extinct every day (phenomenal aint it?!). Much of this is due to humans taking more than they need, and not even giving it to those people who need it most. A major premise of evolution and natural selection is that animals evolve to take what they need to survive and successfully reproduce. IMO, many humans are doing more than this, and other animals are suffering for it. But that's not what this topic's about so let's not argue about it
As for the betta/parrot/dog comparison - yes these animals have been selectively bred to the point where many of their natural (& far more desirable) traits have been lost. I still love these animals, but I definitely see where you're coming from, & agree with you - but we'll never manage to stamp that out, so we should just do our best for them. IMO, though, taking the DNA of one animal & implanting it into another (ie. CROSS-breeding, as opposed to SELECTIVE-breeding) is not a good thing to be doing. As TorPeteO beat me to saying

- aside from the cruelty claims and all that, it raises the question of where will we stop? It might sound good now, but in the future, I know I don't want pigs to fly or donkeys to talk lol.
Anyways, that's my 2 bobs worth. Happy arguing all!!
Michelle.