Using a “resident-intruder” protocol, we observed spacing strategies and agonistic behavior in the African electric catfish, Malapterurus electricus, as it encountered conspecifics and equal-sized members of three other species (a bichir, a tilapia, and goldfish). M. electricus defended a familiar shelter site. The catfish employed different locomotor and electric behavioral strategies, depending on the intruder species. In conspecific interactions, M. electricus engaged in ritualized fights, including lateral and open-mouth displays, occasionally escalating to bites. Electric organ discharges were rare. In contrast, in interspecific encounters contacts were limited to brief touches with frequent use of electric organ discharge volleys. Our data indicate that M. electricus discriminates between con-specifics and other species. We postulate that such a discrimination may be mediated by chemical and/or mechanical cues.