Hi Evilss!
I have 5 small triggers together in my 180 FO. They get along great!!! I'm hoping that they will continue to get along as they grow. I've heard that triggers can become very agressive as they mature. I've also heard that they can turn on tank mates.
I'm always watching for aggressive behavior and am prepared to make any changes necessary should anything change. <smile>
(So far, I think my undulated is nipping at my flame angel. I tried to put the angel in one of my reef tanks; but, have been unsuccessful.)
My triggers in order of introduction: humahuma, niger, eyeliner, undulated and clown. The clown is the largest at 3.5" and the undulated is the smallest at 1.5".
Hope this helps!
Linda