Purple Tangs are beautiful fish but they could be mean as hell. A friend had one and was peaceful to all fish in the tank, one day he decided to get a Copperband Butterfly, and as soon as that fish when in the tank, the Purple Tang immediately went after it and did not stop, to the point that the fish was so scared that he went into the fish net by himself. I had a beautiful Copperband Butterfly for many years after that....lol.I agree with Chris, and I also had a problem with one of my tangs harassing newcomers. I was able to catch him, and put him in a container inside the tank for several weeks, and once he was out of jail he become a model citizen.