Size, more than colour, drives dyadic interactions in sub-adults of a colour polymorphic cichlid

Abstract Social and aggressive behaviours often affect the fitness of multiple interacting individuals simultaneously. Here, we assessed dyadic interactions in a colour-polymorphic cichlid fish, red devil, Amphilophus labiatus. We found that sub-adult devil pairs smaller body size interacted more, were more towards each other, than comprising larger individuals. Interactions did not significantly differ between colour morphs, i.e. dark, gold heterotypic pairs. Interestingly, within broad range parameters, an automated measure time two fish spent close proximity was accurate proxy for their level aggression, as measured by observer from video recordings. These results show that, devils, (aggressive) depend on size, but morph, In addition, support use data-gathering approaches appropriate tool studies aggression.