I have a 125 gallon tank with a yellow tang and a purple tang aside from some others. Last Friday I decided to buy two additional yellow tangs believing that 3 of them would not fight. My mistake. What happened is that the two new comers engaged in a constant fight and creating havoc in the tank. The old yellow tang and the purple tang are acting like police and each one is taking care of the new ones preventing the constant fighting. What I fear is an outcome of itch. Any ideas???