The role of tactile interactions in flight responses in the Bronze Cory catfish(Corydoras aeneus)

One of the primary functions of animal aggregations is defense against predators. Many social animals enjoy reduced predation risk as a result of grouping, and individuals within groups can benefit from information transferred by their group-mates about a potential predator. We present evidence that a tactile interaction behavior we term ‘nudging’ substantially modified group responses to a potential threat in a highly social catfish species, Corydoras aeneus . These catfish deployed nudges during flight responses, and these nudges were associated with a greater likelihood of group cohesion following a threat event. Increased nudging behavior resulted in longer flight responses. In addition, individuals that perceived the threat first were more likely to initiate nudges, implying that nudges could be used to alert group-mates to the presence of a threat. Taken together, our results suggest that tactile communication plays an important role in gaining anti-predator benefits from sociality in these fish.