Peace is nice and what I strive for. I hate watching fish fight. I have 8 tangs in an 84x30x25" tank with no aggression other than a occasional tail swipe. I've had most for a few years with one 8years. I'm hesitant to add any fish and disrupt the harmony but I do have a Niger in observation to give a try. He's small so I'm hopping it will go well. He'll probably be the last addition.Yellow and bristle tooth are probably the easiest to get that to work with. I've got 5 tangs right now in 230 gallons and there has been some aggression, but eventually all the tangs ganged up on the angel and since I pulled the angel it's been peace.