Evaluation of tuna by‐product meal as a protein source in feeds for juvenile spotted rose snapper L utjanus guttatus

This study evaluated the use of tuna by‐product meal ( TBM ), a locally produced feed ingredient, as a replacement for fish meal ( FM ) in diets for spotted rose snapper, L utjanus guttatus . Six isonitrogenous compounds [480 kg −1 crude protein ( CP ) and isoenergetic diets (21 kJ g −1 )] were formulated to replace 0 (D‐0%), 10 (D‐10%), 20 (D‐20%), 30 (D‐30%), 40 (D‐40% or 50% (D‐50%) of FM protein with TBM protein. Each diet was fed to four replicate groups of spotted rose snapper (initial weight 5.4 g ± 0.04 g) to apparent satiation three times a day. After 8 weeks of feeding, the fish gained 4–5 times their initial weight. Spotted rose snapper fed D‐30% had a significantly higher specific growth rate (2.7% day −1 ) than fish fed the other diets containing lower or higher amounts of TBM . Haematological parameters and whole‐body proximate composition were unaffected by diet ( P  >   0.05). The ADC for protein and energy in D‐0%, D‐20% and D‐30% were significantly higher than those for the D‐40% and D‐50% groups. A broken line model indicated that 262 g kg −1 TBM in the diet would yield maximum growth of the spotted rose snapper. The results of this study demonstrate that TBM is an acceptable ingredient for replacing 25–30% of dietary protein from FM in spotted rose snapper diets but that higher replacement levels reduce fish performance.