During a dive in the coral reef of the Red Sea I met two Rusty Parrotfish who were fighting each other in a really aggressive way, as you can see from the video. They will have had their good reasons. Generally we have noticed a good cohabitation between fish of the same species and I don’t remember to have witnessed a similar scene. Surely they fought to defend the territory, in fact we know that during the mating period the fish create their own Harem and do everything to defend it. In fact, you can see that one of the Parrot fishes eventually has to give up and is forced to leave.