Ecology of some species of catfishSynodontis (Pisces: Mochocidae) in the Kpong Headpond in Ghana

Synopsis Some aspects of the ecology of the freshwater catfishSynodontis (Pisces: Mochocidae) in Kpong Headpond (Ghana) were studied. Five species were encountered, namelySynodontis schall, S. gambiensis, S. ocellifer, S. velifer andS. eupterus. S. ocellifer andS. velifer were not recorded in the area before impoundment and might have entered the headpond as eggs or young from the main Volta Lake. Length: weight relationships for the two most important species can be described by the equations: Log W = - 1.76 + 3.12log L (maleS. schall), Log W = -1.33 + 2.89log L (femaleS. schall) and Log W = - 0.39 + 2.07log L (S. gambiensis, sexes combined).Synodontis is omnivorous and generally browses on benthic deposits. Adults feed mostly on chironomids, plant material and aquatic insects. The genus displays sexual dimorphism by having a short urino-genital papilla in most adult males. ForS. schall, one season of major spawning activity occurs per year from mid to late September with first time spawners between 20.0–30.0 cm SL. TheSynodontis species studied lay between 2000 to 209000 eggs per spawning season.