Use of High Percentages of Soy Protein Concentrate as Fish Meal Substitute in Practical Diets for African Catfish, Clarias gariepinus (Burchell 1822)

Abstract

The effects of replacing high percentages (50%, 75% or 100%) of dietary protein from fish meal with soy protein concentrate on growth, diet utilization, and carcass composition of the African catfish, Clarias gariepinus, was evaluated. Supplemental methionine was added to the diet formulation in which soy protein concentrate replaced 100% of fish meal protein. Diets were formulated (420 g crude protein/kg and 17.5 kJ gross energy/g dry diet) and fed to catfish fingerlings (13.1±0.5 g) to apparent satiation twice daily for 70 days. Replacement of 50% and 75% of fish meal protein with soy protein concentrate did not affect growth, feed utilization or carcass composition, which were similar (P > 0.05) to those fed with the control diet. At 100% replacement, growth and feed utilization were depressed and slightly inferior hematological characteristics were observed, compared with the other treatments. Liver histology of catfish fed any of the diets showed no alternations. Results indicate that 75% of fish meal protein in catfish diets can be replaced with soy protein concentrate and that catfish can effectively utilize supplemental methionine, thereby allowing up to 100% of the dietary protein from fish meal to be replaced by soy protein concentrate.