Juvenile Convict Cichlids Prefer Shoals Over Potential Shelters

Abstract

Successful strategies of predator deterrence or avoidance are necessary for juvenile organisms to survive to adulthood. Individuals should balance the benefits and risks of any strategy they choose. One strategy used by many fish species is shoaling by forming a loose grouping of conspecifics. This may deter predators through dilution or confusion, though it also increases competition between shoal mates. Another strategy is hiding to avoid predation, though hiding spots are only effective to avoid visual predators and may also be used by predators. Juvenile convict cichlids (Amatitlania nigrofasciata) were given a choice between a shoal of juvenile conspecifics and a potential shelter (plants/rocks), in the presence and absence of a predator (Parachromis dovii). We predicted that the fish would prefer the shoal when the predator was present and would prefer the potential shelter when the predator was absent because while shoaling is a predator deterrent it increases competition for resources. We found that the juvenile convict cichlids preferred to spend more time with a shoal than the potential shelter and did not prefer the potential shelter alone, and this preference did not change with predator presence. This suggests that not only did they prefer the shoal, but that they may have been avoiding the potential shelters, indicating a flexible strategy.