Hormonally derived sex pheromones in fish: exogenous cues and signals from gonad to brain.

Living in a medium that can limit visual information but readily exposes the olfactory organ to hormonal compounds released by conspecifics, fish throughout their long evolutionary history have had both clear cause and ample opportunity to evolve olfactory responsiveness to these potentially important chemical cues (hormonal pheromones). Indeed, water-borne steroids, prostaglandins, and their metabolites are detected with great sensitivity and specificity by the olfactory organs of diverse fishes, and exert important effects on reproductive behavior and physiology in major taxa including carps (goldfish), catfishes, salmon, and gobies. Best understood are goldfish, where periovulatory females sequentially release a preovulatory steroid pheromone and a postovulatory prostaglandin pheromone that dramatically affect male behavior, physiology, and reproductive fitness.