International Journal of Comparative Psychology

I report an observation of possible play behavior in an individual captive Vlaming's unicornfish (Naso vlamingii). The fish was documented performing locomotory interactions with the filtered stream of water from the return nozzle in its aquarium. Such behaviors conform to existing definitions of play behavior. Animal play is traditionally imagined to be restricted to mammals and birds, with research on this type of behavior remaining scarce within other animals. This finding thus expands upon the ubiquity of play in understudied vertebrate taxa.