Geometry of a selfish school: defence of cichlid young by bagrid catfish in Lake Malawi, Africa

" Three pairs of parental Bagrus meridionalis, a predatory catfish, were observed defending a mixed brood of their own young and those of cichlid fish. The catfish actively excluded the cichlid young from the centre of the school, indicating that the catfish parents can distinguish catfish from cichlid young. Since the peripheral young are more susceptible to predation this behaviour is adaptive for B. meridionalis. However, it might also benefit the cichlid young since they were actively protected by the parent catfish "