Nile tilapia
Groups of Nile tilapia establish social hierarchies in which the dominant males have priority for both food and mating. Circular nests are built predominantly by males through mouth digging to become future spawning sites. These nests often become sites of intense courtship rituals and parental care. Like other fish, Nile tilapia travel almost exclusively in schools. Although males settle down in their crafted nesting zones, females travel between zones to find mates, resulting in competition between the males for females.