Hormones and sexual behavior of teleost fishes

Fishes have radiated throughout all aquatic environments, and this is reflected in an extraordinary diversity of mating systems and reproductive behaviors. Many species present a remarkable plasticity in their sexual displays, as exemplified by fishes that change sex or adopt more than one reproductive tactic during their lifetime, and this plasticity is mediated by hormones. Further, the fish neuroendocrine system is well conserved, and the mechanisms of hormonal action share similarities with those of other vertebrates. This makes fishes interesting models for the understanding of the endocrine regulation of sexual behavior. In this chapter, the role of hormones and neuropeptides in the modulation of fish sexual displays is reviewed. Endocrine modulation of both male and female sexual displays is covered, as well as what is known about the brain circuits targeted by these hormones. Recent advances and technological developments that have been increasing our understanding of fish behavioral endocrinology are highlighted and topics for future research in this field are identified.