Nonapeptides and Social Behavior in Fishes

The nonapeptide hormones arginine vasotocin and isotocin play important roles in mediating social behaviors in fishes. Studies in a diverse range of species demonstrate variation in vasotocin neuronal phenotypes across within and between sexes and species as well as effects of hormone administration on aggressive and sexual behaviors. However, patterns vary considerably across species and a general explanatory model for the role of vasotocin in teleost sociosexual behaviors has proven elusive. We review these findings, examine potential explanations for the lack of agreement across studies, and propose a model based on the parvocellular AVT neurons primarily mediating social approach and subordinance functions while the magnocellular and gigantocellular AVT neurons mediate courtship and aggressive behaviors. Isotocin neuronal phenotypes and effects on behavior are relatively unstudied, but research to date suggests this will be a fruitful line of inquiry.This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.

► Arginine vasotocin and isotocin are important mediators of sociosexual behavior in fishes.
► Behavioral effects of administering exogenous AVT vary substantially across species.
► Different AVT neuron populations may mediate distinct types of sociosexual behaviors.
► Isotocin effects on behavior are relatively unstudied, but likely to be important.