Aggression supersedes individual oxygen demand to drive group air-breathing in a social catfish

1) Group-living is widespread among animals and comes with numerous costs and benefits. To date, research examining group-living has focused on trade-offs surrounding foraging, while other forms of resource acquisition have been largely overlooked. 2) Air breathing has evolved in many fish lineages, allowing animals to obtain oxygen in hypoxic aquatic environments. Breathing air increases the threat of predation, so some species perform group air breathing, to reduce individual risk. Within species, air breathing can be influenced by metabolic rate as well as personality, but the mechanisms of group air breathing remain unexplored. It is conceivable that keystone individuals with high metabolic demand or intrinsic tendency to breathe air may drive social breathing, especially in hypoxia. 3) We examined social air breathing in African sharptooth catfish Clarias gariepinus, to determine whether individual physiological traits and spontaneous tendency to breathe air influence the behaviour...