Individual recognition in a cooperatively breeding cichlid: Evidence from video playback experiments

Most theories of social behaviour and cooperation assume that animals can recognise other individuals, but this is rarely tested. Using Neolamprologus brichardi, a cooperatively breeding cichlid fish, we monitored behavioural responses to (1) real fish versus video images of fish; (2) mate versus neighbour and (3) video images of mate versus video image of neighbour. All tests were controlled for size and sex. Fish reacted appropriately to the playbacks, although responses to videos were not as strong as to real fish. Both males and females fought against the images of stranger and neighbour fish and they courted images of mates. These results confirm that the cooperatively breeding fish, Neolamprologus brichardi, recognises individuals based on vision and that video playbacks contain sufficient information to facilitate recognition.