Sex-role differentiation in feeding and defence of young by a biparental catfish, bagrus meridionalis

Parental feeding of young is well documented among endothermic vertebrates and social insects but is rare among fish, Bagrus meridionalis parents feed their young in a manner analogous to birds and social insects. Females feed trophic eggs to the young and the male burrows to expose benthic invertebrates for the young to eat. These behaviour patterns and parental defence of the young were directly observed with remote video-cameras. Division of labour between parents exists not only in the feeding of the young but also in their defence. Role differentiation in defence of the young was greatest when the young were subjected to the most attacks from predators. The female attacked and chased potential brood predators at the edge of the school while the male remained with the brood, executing more frontal displays. On the other hand, as the young grew older and predation decreased, both parents engaged in more sex-specific food provisioning behaviour such as egg release by the female and nest burrowing by the male. Parental role differentiation and monogamy in this species might have evolved both to enhance the growth rate of the young and to reduce their susceptibility to predation.