Ultimatereef.com TOTM keeps a yellow tang in a 30gal...

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I have always sympathized with the Tang police at heart however nowadays I wonder whether all of us aren't guilty of the same thing. I have snorkeled in Hawaii beside a school (? shoal) of 100 to 200 yellow tangs. Within a few seconds they moved over an area twice the size of my house. I agree that keeping Tangs in a nano is a horrible idea. The question is, am I any better having Tangs in my 120? Or anyone else I've seen keeping Tangs in a 4, 6, or even 8 foot tank.

Some fish I have seen while diving seem to stay in a small territory, for example a group of Royal Grammas each staying near its own little spot on the reef. Fish with this sort of swimming habit seem suitable for aquariums. Fish that swim over large areas constantly don't seem fit for an aquarium of any size.