The fish sampled at the start and end of the trial were cooked in an autoclave at 120 °C for 20 min, homogenized, and dried at 105 °C for 24 h prior to chemical analysis. The autoclaving method was described by Officer and Morris (2000). Samples of the ingredients and formulated diets were ground into a fine power (diameter: 0.25 mm) with a laboratory grinder.