I know some people are seriously against this but I had to buy some of these guys since they're so different. I already had some zebra danio's in my tank and so I got a half dozen of the pink guys (and girls!). They the same fish, just a differnt color and yes they do glow under black lights, its pretty cool to turn all the lights off and turn a black light on over the tank and just see these intense pink fish swimming around. I was worried my black ghost knife might find them a tasty treat but I've had him for years and he's been quite peaceful even with the smallest of fish in the tank. So far so good!
I think I would be more against it if there was clear harm to the fish, either their lives being shortened drastically or getting sick often but for the most part they're suppose to be just as lively and loveable as the normal zebras. Supposedly the regular danios wont mate with the colored ones, they dont find each other attractive? I heard that the modified ones dont have the stamina that the natural ones have but its hard to judge in a tank where they all seem extremely active and healthy. Oh well.....