They are not as active swimmers as big tangs, but IMO they still should be provided with some good swimming space. I'm sure it could be done, but I wouldn't try it.
They are awfully sensitive fish, and any source of stress can make the difference IMO. The bigger the tank, the lower the stress (on at least that one vairable).
I'd keep a tang in a 55 before a CBB, but a lot of others would say the opposite.