When i add in new fish, to keep my Atlantic blue from pestering them, I place a mirror at one end of the tank. the Tang is usually then too preoccupied with his reflection to care about a new addition. 5 days of mirror and the new fish is usually all settled in and life is good. I recently added a powder brown and Blue hippo tank to my tank. the Atlantic blue was not happy about the Powder brown, and as soon as i put the mirror on, the chase ended. now they peacefully co-exist.