Growth, Feed Utilization and Haematology of Clarias gariepinus (Burchell,1822) Fingerlings Fed Diets Containing Different Levels of Vitamin C

Problem statement: In an effort to increase growth, improve feed utilization, reduce stress and prevent certain diseases, a 14 week feeding trial was conducted to determine the effects of different levels of dietary vitamin C (ascorbic acid) on growth, feed utilization and hematological changes in Clarias gariepinus fingerlings. Approach: Diets were formulated to contain 0, 50, 100, 150, 500, 1000 and 1500 mg L-ascorbic acid kg^-1 of feed contributing 0, 0.05, 0.10, 0.15, 0.5, 1.0 and 1.5% to the formulated diets respectively. Fish of mean weight 10.12±0.7 g were fed on experimental diets in triplicate groups. Weight gain of fish fed diet with 0% of vitamin C were significantly (p<0.05) lower than those fed on supplemented vitamin C diets. Fish fed diet with 1.5% of vitamin C showed a significantly (p<0.05) higher weight gain than fish fed on other diets. However, there were no significant (p>0.05) differences in weight gain among the fish fed diets containing 0.05, 0.10 and 0.15% of vitamin C. Generally, fish fed vitamin C supplemented diets showed better growth rate, feed conversion ratio and protein efficiency compared with those without vitamin C supplementation. Results: The results of hematological analyses of fish showed that red blood cell, white blood cell, haemoglobin concentration and packed cell volume were not significantly (p>0.05) affected by vitamin C supplemented diets. Fish fed the vitamin C-free diet begin to show deficiency signs such as erratic swimming, flashing, skin darkening and reduced growth at 12 weeks of feeding trial. Conclusion: This study indicated that 50 mg kg^-1 of ascorbic acid is sufficient to prevent C. gariepinus fingerlings from developing clinical symptoms relating to vitamin C deficiency. A mega dose of 1500 mg kg^-1 of ascorbic acid gave maximum growth performance and feed utilization efficiency.