I have 4 yellow tails, a domino, and a 3 stripe. They get along fine in my tank, and they pick on each other. I have them in a 125, and one of the yellow tails is laying eggs about every other week. I'm going to add another couple of dominos and 3 stripes so that they fight each other, because right now they pick on some new firefish I have and each other. If you give them enough of their own kind to fight with, they won't really bother anybody else.
By the way, the domino also lives in anemones and corals, just like a clown, so it's a cool fish to add. When I was snorkeling in Bora Bora, I saw a huge long tentacle anemone about 2-3' across (I think it was a long tentacle, not really sure) with 30+ dominos in it all hanging out together, and also small coral heads with multiple 3 stripes living in it. Again, as long as you provide them their own species to battle with, they shouldn't bother other inhabitants.
[ August 16, 2001: Message edited by: davelin315 ]