Abstract:
Studies on food items occurrence, composition and selectivity in riverine cyprinid species in River Kuja basin have not been adequately addressed towards habitat quality assessment for Lake Victoria basin. In particular literature on food items selectivity and composition by weight for Labeobarbus altianalis is scanty. Therefore, a study was conducted on the distribution, abundance and the diversity of food items in the habitat, occurrence, composition and selectivity in the guts of L.altianalis in the Kuja-Migori River between November 2016 and August 2017. Five stations were chosen based on longitudinal occurrence (Kegati, Ogembo, Kanga, Gogo dam and Wath Onger) and sampled during the rainy season(November to March) and dry season (April to August). July and August experienced long rains. Stomach contents of 1032 specimens were collected by electrofisher and analysed. The major diet of fish <5 cm total length was found to be insects, zooplankton and algae, bigger fish fed on wide range of food items including plant matter and insects. Detritus, macrophytes and insects were found to be the dominant food items in all size classes, whereas the contributions of fish scales, zooplankton and phytoplankton were low. Ivlev`s of electivity (E) indicated that the most preferred food items in the upper section of the river during the dry season were Diptera (E = +0.64) and Ephemeroptera (E = +0.63), in the lower section the most preferred were Diptera (E = +0.72) and Decapoda (E = +0.60). Comparatively, during the wet season in the upper section of River Kuja basin the most preferred food items was Odonata (E =+0.72) while Pulmonata and Hirudinia were mostly avoided (E = -1). Based on the results it can be concluded that Labeobarbus altianalis is omnivorous in its feeding habits in River Kuja Basin.
