Background. Prochilodus magdalenae is a neotropical fish that synchronizes reproduction with flood river pulses.
Methods. We used an endocrine method to test the influence of hydropeaking on hormone production related with reproduction. We analyzed P. magdalenae reproduction in individuals from two sectors of a Neotropical river basin: one with natural flow and the other with a regulated hydrological regime.
Results. In the section of the basin with natural flow we found that the production of hormones related with fish reproduction (FSH and LH) was correlated with the gonadosomatic index, while in fish experiencing hydropeaking due to hydroelectric operation no such correlation was detected.
Discussion. We conclude that potamodromous fish reproductive hormone production is sensitive to changes in water level/discharge, consequently, fish exposed to hydropeaking receive ambiguous stimuli that affect hormone production, reproduction synchronization with environmental cues, and ripening, which are essential for reproductive success.