I have a rare Black tang that I had to have the LFS house for me when I tore down my tank and sold my house. He was doing great. Started out about quarter sized, and grew to be 6-7 inches long at the LFS. I had have it baby sat there for over two years while I got my new tanks setup. It spent a lot of his time in a 75 gallon. Thankfully a lot of his juvenile life. When I put in my 340, the first thing he did was swim in small circles. Not expecting a lot of room. Now, after having been in there for just over 2 weeks. He constantly swims the full length of the tank. He swims fast and furious. It's 6ft by 3 ft wide and he'll swim up and down and doesn't stop. I've had tangs before, but this guy is an athletic tang. It's funny because I got a large rabbit fish with him (about 6-7" in size also) he's fat, and he tries to stick with the tang as much as possible but he gives up. He follows lazily behind the tang and then waits for him to come back then will swim with him, then let him get ahead and lap him. Heh. I wonder if my 340 is large enough for the black tang. He seems happy. Eats great, swims all over, pecks at rocks. I think he's happy, but, tangs are something that need special care. As with all our cool inhabitants, must research their needs.