Arginine vasotocin neuronal phenotypes, telencephalic fiber varicosities, and social behavior in butterflyfishes (Chaetodontidae): Potential similarities to birds and mammals

►Comparison the arginine vasotocin system in seven species of butterflyfishes that differ in social behavior. ►The density of arginine vasotocin varicosities within the septal homolog of fishes is likely related to aggression. ►In most cases, aggressive species have larger arginine vasotocin preoptic area gigantocellular cells. ►Arginine vasotocin within the telencephalon of fishes likely plays an important role in social behavior and may function in a similar manner to that of AVT / AVP in birds and mammals despite having cell populations solely within the preoptic area.