Effect of different levels of phosphorus on growth and mineralization in African giant catfish Heterobranchus bidorsalis (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 kgA^-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 (P 0.05) growth performance and feed conversion ratio (FCR). Fish in T1 and T2 had the highest (P 0.05) FCR. Carcass protein was the same in T5, T6, T7, T8, T9 and T10, which was higher (P 0.05) than in T1, T2, T3 and T4. Carcass fat content was highest in fish in T1 which also had the lowest water content. P and Ca concentration in fish carcass increased linearly and was highest (P 0.05) in fish in T11, while Mg and Zn were highest (P 0.05) in fish in T5. Data from the study suggest 12.3 g P kg^-1 diet as optimum requirement for the growth of Heterobranchus bidorsalis.