We raised ours from a very small juvenile. Very timid until maturity. Once around say 4-5" he was the boss. Any fish that resembled him like a copperband butterfly, etc, of the same size he would really harass to the point of having to remove said fish. Typically if it was a small juvenile, the tang wouldn't bother. Honestly, we would never have another tank without a purple tang, I highly recommend one but try to find a small one. You know we never quarintine and the purple tang was very robust. He developed crypto once but fed a very high quality diet it never showed up again in over 8 years plus that guy survived quite few moves. I vote get one!