Trophic relationship of fish species in Ogbese River, Ado-Ekiti, South-Western, Nigeria

This study was conducted to determine the trophic relationship of Clarias gariepinus , Parachanna obscura , and Oreochromis niloticus collected from Ogbese River, Ado Ekiti, South-Western, Nigeria between June and September, 2017. The fish specimens were examined and their stomach contents analyzed. Numerical, frequency of occurrence and volumetric methods were employed in this study. The result of the analysis showed that C. gariepinus , P. obscura and O. niloticus fed on similar food items. These were mainly algae, nematode worms and insects. The stomach content of C. gariepinus consisted of animal and plant materials, planktons (phytoplankton and zooplankton) as well as detritus. The dominant animal material found was flying termite Cryptotermes species with 55.23% and plant material was maize seed with 16.62%. The stomach of P. obscura consists mainly of plant and animal materials, planktons and unidentified food items. Algae represented by Euglena species accounted for 66.67% and Nematode worm (22.22%) was the dominant animal material. The stomach of O. niloticus consisted of plant and animal materials, detritus and mud. Filamentous algae represented by Spirogyra spp. 75.42% was the dominant plant material. Thus, each species depended on more than one food source. However, overlaps existed, fishes were found to feed on more than one type of food item which reduced competition and encouraged coexistence. Based on the food items encountered for the period of study in the stomachs of C. gariepinus and P. obscura are omnivorous while O. niloticus is herbivorous in Ogbese River, Ado-Ekiti. The relative importance index (RI) showed that the most important food items in C. gariepinus , P. obscura and O. niloticus are insect (45.0%), algae (59.91%) and (62.42%), respectively .