Determination of Optimum Calcium and Phosphorous Ratio for the Production of African Catfish Clarias gariepinus (Burchell, 1822)

Optimum calcium-phosphorus (Ca/P) ratio for the growth of African catfish was investigated over a 70-day period with a basal diet formulated and supplemented with Ca/P ratios of (0:0, 1:0.5, 1:1, 2:1.5, 3:1 and 3.5: 1.5) respectively. The results showed that the mean weight gain and specific growth rate increased from the fish fed the control diet up to the fish fed diet with Ca/P ratio of 2:1.5, and then declined consistently to the fish fed diet with Ca/P ratio of 3.5:1.5. Addition of Ca and P in the diets significantly increased the carcass ash, while feeding the fish with the control diet supposed to be imbalance in Ca/P ratio elevated the carcass fat and moisture. The increase in carcass ash consequently resulted in increase (P<0.05) in carcass minerals (Ca, Mg, P, Zn and Fe) in relation to fish fed the control diet. In conclusion, the study suggests Ca/P ratio of 2:1.5 (1.33:1) as the optimum for the production of African catfish

Effect of protein deficient diets on the growth and carcass protein ash ratio of African catfish Clarias gariepinus (Burchell 1822)

As the prices of fish feed ingredients continue to soar due to economic and environmental challenges, many fish farmers now produce practical fish diets deficient in protein, to minimize costs and maximize profits. This study evaluated the effects of such diets on the growth performance and carcass quality of African catfish, Clarias gariepinus. Five dietary treatments used contained 25%, 30%, 35%, 40% and 45% protein, respectively. Fish were fed for 70 days and the results showed high and improved growth performance in relation to the increasing dietary protein levels. Carcass protein, ash and minerals correlated positively with increasing dietary protein levels while the lipids had inverse relationship. Generally, fish fed diets of 25-35% protein had lower performance than those fed the control diets of 40 or 45% protein reported as the requirements for the fish. However, and in all cases, there were no differences in the performance of fish fed 40 or 45% protein diet, indicating no significant additional benefits from feeding the fish with 45% protein diet. The results also suggested the protein requirement of the fish to be above 35% and about 40%. The carcass protein-ash ratio was observed to be constant and ranged between 4.08 and 4.82. © JASE

Effect of different levels of phosphorus on growth and mineralization in African giant catfish <i>Heterobranchus bidorsalis</i> (Geoffrey Saint Hillarie, 1809)

Eleven diets (D1-D11), designated as treatments (T1-T11), supplemented with different levels of inorganic phosphorus (P) (Ca2PO4) were fed to Heterobranchus bidorsalis (10.8 ±0.02 g) to determine the optimum P requirement. D1 - D11 contained total P of 10.2, 10.4, 11.0, 11.9, 12.3, 12.6, 13.4, 13.9, 14.2 14.7 and 15.4 g kg-1 respectively. After 84 days of feeding trial, there was increase in fish growth up to T5 with 12.3g P kg-1 diet, followed by consistent decline in growth towards T11 with the highest P content. However, fish in T5 had the best (