I currently have 3 in 2 different tanks - 2 in a 220g reef, and 1 in a 125g semi-aggressive fish only. The large one in the reef tank is fairly passive, he only bothers the other shrimp from time to time, but leaves the fish alone. The one in the 125g is a real terror though. He hangs upside down in his cave all day long, and extends his claws and charges whenever one of the fish swim through his home. He even bullies the 4" picasso trigger I have, though that may change with time. When I added a small 3" jeweled puffer to the tank, it first swam into the cave to avoid the trigger. The coral banded grabbed him with both claws and started to drag him to the bottom of the tank before he figured out what was going on and swam away. Really surprised me. Seems that there is a big variability with temperaments.