To answer your last question I say a very loud YES! These are animals too. Just because they are not furry and petable (although I have had fish that let me pet them) I don't think they should be viewed as disposable. I think that is one of the major problems with this hobby. Too many people don't research to see how long these fish can and should live. They think 3-5 years is a good long life. The fish has just barely reached adulthood then. Or they view it as moving art, like those in that thread about the really expensive tanks. They don't even want to feed them. I know the argument is made that the fish could just as easily get eaten or die of other causes in the wild, but I think that is a moot point. Once we take them out of the ocean they are our responsibility. We should be doing everything we can to give them the best possible chance to live as long as possible. While some Tang maybe okay in a small tank for an extended period of time, doesn't mean they all will. Unfortunately the fish can't tell you he is stressed. He only shows it when he is sick and sometimes it is too late at that point. I say always error on the side of caution.