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.