The role of visual and olfactory cues in social decisions of guppies and zebrafish

Vision and olfaction are expensive to maintain, and in many taxa there appears to be a trade-off in investment between the two sensory systems. Previous work has suggested that guppies, Poecilia reticulata, and zebrafish, Danio rerio, may differ in the relative importance they place on these two senses in social interactions. In this study, we directly examined this issue by experimentally contrasting olfactory and visual information in social situations. In the first experiment, we found that guppies spent more time where conspecifics were visible than where they could smell them. In contrast, zebrafish spent significantly more time in an empty compartment containing the smell of conspecifics than in a compartment in which they only saw them. The difference was not large, suggesting that both species integrate various types of information to locate a nearby shoal. In two subsequent experiments, we studied the role of vision and smell in the discrimination of the quality of the social ...