Not exactly sure what the deal is with clown tangs but in the 18+ years that I have been working in the aquarium business it has always seemed to be the same thing with this specie of tang, they don't ship well and the odds of them surviving past a month in captivity seem to be less than 50% if even that, regardless of how well they may seem to be doing right up until the time of death. Unless you want to flip a coin on a clown tang I wouldn't purchase one unless you know it has been surviving in an aquarium for at least a month if not longer. Seems those that make it past a month are extremely hardy fish as well as, like Superman stated above, possibly the most aggressive of all the surgeon fish regardless of size. If you are ever considering adding one of these beautiful fish to a reef tank make sure it's one of the last fish you add to the system. Given enough time it will more than likely dominate over all other tangs in the tank. Not stopping there, clown tangs often bully angels and butterfly fish as well as many other reef fish. Adding tangs, angels or butterflies into a system with an already well established clown tang often results in the poor newcomer being shredded before your eyes within minutes. As with any particular individual specie of fish there are always exceptions. I don't doubt for a minute that there are people out there who will tell you that they have, or had, a clown tang whom is/was a perfectly friendly community fish. Then again, I've heard several people over the years tell me they keep tiger barbs with angelfish without any problems...
p.s. I myself can't resist keeping a clown tang in a reef tank. IMO they are one of the most beautiful of all the tangs. Comical at times in their fearlessness...
