I have a 125 gallon main display tank. As of right now I have a powder blue tang. I am wanting to add a unicorn or a shoal tang to the tang. How can I do this without one of them killing the other. I had thought when I get a new tang to get one that is smaller than my powder blue who is about 3 to 4 inches long. This way the powder blue does not feel threatened. I also thought about taking the powder blue out of the mains display tank and put him into another tank for about two weeks and the introducing him and the other tang to the tank at the same time. Hoping he would have forgot about his established territory by then. Any body have any suggestions how to remedy this situation.