Discharges from the electrical organ of the weakly electrical fish Gnathonemus petersii are recorded through electrodes in an aquarium, they are displayed on an oscilloscope synchronously with the fishes' activities and are rendered audible. Trick pictures show the fish's electrical streamline field as well as it locating good and poor conductors of electricity. While behaving aggressively, the fishes' discharges are recorded and shown in the film.