Highly Repetitive Object Play in a Cichlid Fish (Tropheus duboisi)

Whether play occurs in fishes has long been a contentious issue, but recent observations document that social, object, and locomotor play can all be found in some species of teleosts. However, quantitative studies and those documenting individual differences are rare. We recorded hundreds of occurrences of an unusual behavior in three male Tropheus duboisi. The target behavior of attacking and deflecting an object that rapidly returned to its upright position not only fit the criteria for play behavior, but differed quantitatively and qualitatively among the individuals. This behavior has not been observed in other species of cichlids and other kinds of fishes. The presence or absence of food or other fish either within the aquarium or visible in an adjacent aquarium had no marked or consistent effect on the occurrence of the behavior. Various explanations for the origin and function of the behavior are discussed.