Group cohesion in juvenile weakly electric fish Mormyrus rume proboscirostris.

The current study demonstrated that juvenile Mormyrus rume proboscirostris, an African freshwater weakly electric fish, used their active electrosense in group cohesion. Data also indicated that sight and mechano-reception could play a synergistic role in controlling this behaviour. The developmental change from a larval monophasic electric organ discharge to the adult biphasic waveform was accompanied by a reversal of the fish's social spacing. Light was aversive to social spacing in the younger fish (aged 49 and 65 days), but facilitated aggregation in the older fish (245 days).