 Displays of ritualized aggression in cichlids include a remarkably rapid change in coloration, during which a successfully dominant territorial male assumes a more vivid and brighter coloration while a subordinate or "non-territorial" male assumes a dull-pale coloration.In addition to color displays, cichlids employ their lateral lines to sense movements of water around their opponents to evaluate the competing male for physical traits/fitness.Male cichlids are very territorial due to the pressure of reproduction, males establish their territory and social status by physically driving out challenging males (novel intruders) through lateral displays (parallel orientation, uncovering gills), biting, or mouth fights (head-on collisions of ajar mouths, measuring jaw sizes, and biting each other's jaws).