FOOD OVERLAP BETWEEN THE ALIEN ONCORHYNCHUS-MYKISS AND THE INDIGENOUSFISH SPECIES BARBUS-AENEUS AND CLARIAS-GARIEPINUS IN A MAN-MADE LAKE,SOUTH-AFRICA

The introduction of Oncorhynchus mykiss into the Sterkfontein Dam nece ssitated an investigation of the food overlap between this fish specie s and the indigenous fish species The Schoener index of similarity was used to determine possible food overlap between adult fish of three f ish species in the Sterkfontein Dam, part of the Tugela-Vaal Water Tra nsfer Scheme. Although the data are incomplete, indications are that t he intra- and interspecific food overlap between adult fish of the fis h species Oncorhynchus mykiss, Barbus aeneus and Clarias gariepinus wa s generally large.