The effect of a man-made lake on the diet of the African electric fish Mormyrus rume Valenciennes, 1846 (osteoglossiformes; mormyridae)

The diet of 223 specimens of Mormyrus rume (Mormyridae) from the BiaRiver on which a hydro-electric dam was built in 1959, was studied in relation to locality, season and fish size. A feeding index was computed by combining the occurrence, numerical and weight percentages of the items identified in the stomach contents. This index showed that M. rume in the river ate principally invertebrates, especially chironomid larvae. In contrast, M. rume from the man-made lake contained mostly phytoplankton. This difference was statistically significant. In the lake, chironomid larvae and Bacillariophyceae constituted the main source of the diet of young fish. In larger specimens, Chaoborussp. formed the main part of the diet. No significant temporal variation occurred in the dietary composition. The overall food compositionwas similar in each locality of the Bia River from one period to another. [ABSTRACT FROM AUTHOR]