My friend who has a way overstocked tank has had his clown trigger in a 55g. for about a year and a half know with a volitan lion, miniatus grouper, porcupine puffer, and a snowflake eel. The kid is kind of an idiot because he only listens to the lfs but whatever. They have all been in there doing fine. The trigger is about 6 inches and probably the stupidest fish I've seen because when he feeds them krill and stuff he'll thaw it out drop a few peices in at a time and the trigger will swim real fast back in forth looking for it so he has to put the krill on a stick and put it in front of him.