Mate switching as a function of mate quality in convict cichlids, Cichlasoma nigrofasciatum

Convict cichlids, Cichlasoma nigrofasciatum, were used in the investigation of the influence of mate size on mate switching. Size-mismatched and size-matched pairs were reared in a partitioned aquarium. When the partition was removed, the mismatched pairs re-sorted 46% of the time while size-matched pairs remained intact most of the time. Size determines the dominance relationship between two competing pairs of Cichlasoma nigrofasciatum. When there is a size disparity between the male and the female partner, the pair with the larger male dominates.