Tilapia males will mouth fight and rarely harm each other. Non-gravid females not near spawning, a male will hammer behind the gills, to cause clotting and suffocation. Doesn't sound very bright for survival of the species, but dominant males hate all other Tilapia that are not ready to drop eggs and are fiercely territorial. Btw, the larger the dominant male, the larger the area it will kill female Tilapia in.
