They are a more peaceful tang, but each fish has it's own personality. I personally had a kole that was a holy terror to wrasses and had to be removed.I have a 75g with 2 T/P Clowns, Firefish, Melanurus and Flasher Wrasse. Setting up the QT again today and decided to get a Kole Tang. I read that they can be somewhat aggressive to other fish, mostly other algae grazers. Should I worry about it with the stock I have now?