yellow tangs

i am planning on geting a new tank can i put a yellow tang in a 29 gallon? or do i need a bigger tank?

We just added some new fish to our salt water tank, including a copperbanded butterfly, yellow watchman, and a few others. We initially had a yellow tang and a mandarin gobi. The yellow tang likes to chase around the copperband. (because they're about the same size and color?) My parents...