Faithful fish: territory and mate defence favour monogamy in an African cichlid fish

Abstract. Monogamy is thought to occur when the opportunities for polygyny are constrained by strong intra-sexual competition, or when two individuals are needed to defend a territory, or to feed or defend their young. In Eretmodus cyanostictus, a monogamous cichlid from Lake Tanganyika, parents do not feed young and each sex is capable of caring for all the offspring alone. We used a series of field-based removal experiments to investigate …