Electric organ discharges of the weakly electric fish Gymnarchus niloticus (Mormyriformes) in its natural habitat.

Electric organ discharges (EODs) of Gymnarchus niloticus in its natural habitat (Chari River, Chad Basin) and accompanying ecological data (pH, conductivity, temperature, turbidity, O2 dissolved) were recorded. The EOD frequencies ranged from 204 to 313 Hz (day) and 196-326 Hz (night). In social swimming the range of interfish EOD frequency differences was from 4 to 82 Hz. The EOD frequency seems to decrease with the age of the fish.