IMO i dunno why they is alays a craze to squeeze many tangs in a small let say 4-5 feet tank......... Yes tangs maybe nice but their territorial behavior surely make them loose out to other reef fishes like gobies and anthias and the other very bad point is that they poo alot and that make them another very bad choice to have in a reef tank which require very little dissolved waste in the water. Not saying that you cannot have tangs, but just not that many.