I have a standard 120g (4x2x2) that has one 5" Desjardini sailfin, one 2" yellow eye kole tang, one 3 inch yellow tang, one anthias, three chromis, 2 damsel and one 2.5" maroon, they all happy together even though they bum into each other once in a while. I had been waiting for an used Purple tang and love to add to my collection and see a member in this club selling one. Do you think i have to much fish or tang in the tank? Should I add the purple tang (4 inch)? what is the best way to introduce the purple tang? In the worse case scenario, how can I stop the fight between them (if happen)?