I jsut wanted to say that it is just a fish. Just because it looks better than a goldfish, doesn't make it better... You see, if you really do believe it is cruel to keep this fish in a 29 gallon tank, you should not have any tanks at all- that is unless you can get a 1,000 gallon tank like in their real environment. Even if the tang was in a 150 gallon tank, it still cannot do half the things it would do in the wild..
Are you against fishing? It is cruel for the fish to get a hook in it's mouth and all-
You could say it would be a better investment to put it in a larger tank, because it would live longer.