I have a 140 with 4 tangs in it as well as a few other fish all introduced at different times. A Yellow, Powder Brown, Purple and Naso. The yellow was the first and only problem when new tangs were introduced. I delt with him by putting it in the sump for a few weeks so it lost its teritory. No problems after a time out a couple of times as the new tangs were introduced. All get along great now.