Dragonflies in the diet of the teleostean fish in the Comoe River, Upper Volta, West Africa

The stomach contents of 10 species of entomophagous teleostean fish from the Lower Comoe River, pertaining to the orders Mormyriformes (1), Cypriniformes (I), Siluriformes (5) and Perciformes (3) were examined in March, 1978, in the framework of a project on the side-effects of the insecticides used against the tsetse, and carried out by the Department of Toxicology, Agricultural University, Wageningen, the Netherlands, in cooperation with the World Health Organization. The fish were classed into six size-classes, ranging from II to 40 cm. The dragonfly specimens recovered from the stomachs were all in larval stage, hence they could not be further identified. Adults of Pseudagrion sjöstedti Foerster, P. whellani Pinhey, Orthetrum chrysostigma (Burnt.), O. monardi Schmidt, Trithemis annulata (P. de Beauv.) and T. arteriosa (Burnt.), however, were common on the observation site. Dragonflies were completely lacking in all 36 specimens of the three perch-like species examined, referable to three families of two suborders, viz. Ctenopoma kingsleyae (18; Anabantidae. Anabantoidei), Lates niloticus (6; Serranidae) and Palmatochromis guntheri (12; Cichlidae, both Percoidei), though these contained some trichopteran and chironomid material and, in the case of Ctenopoma, also some crustacean remains.