Antipredator behaviour and suppressed aggression by convict cichlids in response to injury-released chemical cues of conspecifics but not to those of an allopatric heterospecific

In aquatic environments, chemical cues serve as an important source of information for the detection of predation risk. Here, we investigate the response of convict cichlids, Cichlasoma nigrofasciatum, to injury-released chemical cues. We exposed pairs of juvenile convict cichlids first to dechlorinated tap water (control), then later to one of two test stimuli: 1. chemical cues from injured convict cichlids; or 2. chemical cues from injured mosquito fish, Gambusia affinis. Gambusia are allopatric and phylogenetically unrelated to convict cichlids. Gambusia skin was used to control for a general response to injured fish. In response to conspecific cues, convict cichlids significantly increased time spent near the bottom of test aquaria and time under a shelter object. In response to Gambusia skin, convict cichlids tended to increase time spent near the tank bottom but did not increase use of the shelter object. There was a trade-off between antipredator and agonistic behaviours. In response to convict cichlid cues, there was a significant reduction in the frequency of approaches and bites. Gambusia skin extract had no significant effect on aggressive behaviour. These data suggest a species-specific antipredator response to conspecific alarm pheromones in a New World cichlid fish and demonstrate a trade-off between predator avoidance and intraspecific aggression. Further, the presence of an alarm response in this model species sets the stage for the use of chemical cues as a research tool to manipulate predation risk in studies of the interaction between predation risk and reproductive behaviour.