I have a 3.5-4 inch Niger trigger in my 180 gallon mixed reef, got him since he was 2-2.5 inches long. I have clams, starfish, shrimp, hermits, several clown gobies, ect, ect, he does touch a THING! My key is to keep him VERY WELL fed. If you keep him very well fed, he shouldn't touch anything. Good luck!