Abstract: | The electric discharge of Sternopygus macrurus is distinctly different from the discharges of ten sympatric species of electric fish in Guyana, South America. Sternopygus is the first known example of a fish with sexually different electric discharges. Males and females differ in the steady-state frequency of their discharges, and males produce variations in their discharge during courtship. Playback experiments demonstrate that species and sex differences in electric discharges have communicative significance. |