EVALUATION OF AFRICAN CATFISH Clarias gariepinus RESPONSES TO GRADED LEVELS OF ZINC PRACTICAL DIET  

Fisheries <file:///\\wiki\Fisheries> and aquaculture <file:///\\wiki\Aquaculture> contribute significantly to food security <file:///\\wiki\Food_security> and livelihood; therefore, fish and fish products are projected as being among the most widely traded foods.Fish like other animals has requirement for essential nutrients in order to grow properly. Such essential foods are available in the wild for fish to forage extensively to meet their body needs. Factors such as climate change, environment, and season of the year among others determines the abundance and search for these foods. These factors modifies aquatic environment and make it difficult for fish in the wild to forage adequately. Therefore, enough food in the form of artificial diet is required to furnish fish with the nutrients it need out of its natural environment for optimal growth. However, most of the challenges facing feed formulation are related tocost of production and bioavailability for fish optimal growth. Therefore, trace minerals such as zinc which has been recognized to play a vital role forgeneral health maintenance and growth inevery aspect of a living system offers some solutions; however, their deficiency disturbs the wellbeing of the fish.Therefore the biochemical components of fish diet that needsvarying in terms of percent inclusion to render the protein in feed more bioavailable should be encouraged.The objectives of this study are to determine the: required dietary zinc that is essential for juvenile African catfish (Clarias gariepinus) growth, serum biochemical profile, and haematological responses of Clarias gariepinus to graded levels of zinc.

Growth performance and serum biochemical responses of Clarias gariepinus juvenile fed practical diet with graded levels of zinc inclusions at 0, 5.46, 10.96, 16.40, 21.86, and 27.33 mg Zn kg^-1 were investigated. Water quality parameters were monitored throughout the period of the study and compared to have met the tolerable ranges for catfish culture.

The results for the mean weight indicate that there were no significant variations at P>0.05. However, the mean weight pattern revealed a gradual response at a time with respect to dietary zinc inclusion.The SGR, FCR, GFCE, F.I and RGRhad no significant variations.The PCV revealed that there were no significant variations among the values for the fish fed with Diets 3, 4 and 5.The serum biochemistry indicates significant variations in the serum Total Protein (T.P) among fish fed on all the diets, with the highest values in fish fed Diet 4 and the minimum values in fish fed Diet 2.Fish fed dietary zinc revealed slight alteration in haematological and serum biochemistry in response to dietary zinc, however, these responses were not significant at P>0.05. This results indicate that a practical diet with zinc concentration at 5 to 27mg Zn kg^-1appeared not being sufficient for Clarias gariepinus growth response.

Key words:  Food security, zinc practical diet, response, bioavailability, Clarias gariepinus