I put my first tang into my 110g tank, and he hardly ever stops swimming. They are SWIMMERS more than anything else i have. He may only be 2.5" and not much bigger than most of the other fish, but I'm glad i obeyed the Tang laws. The tank recommendation is there for a good reason.
Some fish host, some fish hide, but some fish cruise. The accepted tank recommendations are good.
To the OP, this may have nothing to do with you and is not a targeted post. Just wanted to share something I've noticed