I’ll share my experience with my Atlantic Blue tang which can get large. My tank is a 7ft 210g and only had a few fish… Copperband, Yellow tang, Bicolor & Coral beauty angel, Goby, with random snails and a couple banded shrimp. Not much for a 210g and little to no aggression in the tank. I met someone who was breaking down her 180g tank which included an Atlantic Blue, Foxface, Long Nose Black tang (I really wanted the Long Nose black tang) and a couple wrasses essentially doubling the amount of tank mates. I initially was worried with the CBB being extremely docile and the yellow and black tank both being Zebrasoma which are known to be aggressive. Since introduction the Atlantic Blue (acanthurus coeruleus) is definitely the tank boss because of his/her size being almost double that of the other tangs. I wouldn't consider it overly aggressive but more or less don’t come near me or get chased down. The other tangs including a new Blonde Naso that I acquired could care less about each other and overall the tank is peaceful. My guess would be mainly because of the size of the blue tang keeping everyone in check.
With that being said I somewhat think the Atlantic Blue tang is too large for my tank and can be troublesome. While being an attractive fish it goes bat crazy during feeding time consuming half the food for the entire tank, its clumsy breaking a three year old birdnest coral several times which I finally had to remove and for some reason it randomly does this swish with its tail splashing water that hits the lights and lands on wall and floor. I was thinking of rehoming it but worry that it would upset the peaceful balance that the tank has.
