Even once in a while, my two biggest baddest fish fight. They are both cobalt blue got at the same time from a breeder, are the same hue of blue and are both about the same size. Both are beautiful fish. While they usually control their own half of the tank (55gal 48') every once in a while they get together for a battle. They are the only ones that will lock lips and stay connected like that. Any other fighting in the tank consists of chasing. It's a very interesting show as they go on for about a couple minutes like that. Is this dominance behavior? Are they going to try to kill each other? I can't get a pick as they scatter when I get closer to take a pic.