these fish grow pretty big, around the foot to a foot and a half range. they are pretty tame when it comes to trigger fish. you can pretty much put them with any fish not big enough to fit in their mouths which isn't hard to do. they may be shy at first but in a couple days they start to come out. they are usually the first ones to attack the food you put in the tank and probably will eat right from your hand eventually. they will eat most meaty foods such as mysis and krill. stay away from brine shrimp unless it has been fortified with vitamins. as far as inverts go, you can put cleaner shrimp in there but usually has to be in there before you put the trigger in so now may not be a good idea. he will pretty much eat any shrimp you put in there. crabs, hermits, and snails should be ok.