Growth and feeding responses of the mutton snapper,Lutjanus analis (Cuvier 1828), fed on diets with soy protein concentrate in replacement of Anchovy fish meal

This study evaluated the growth (first phase) and feeding responses (second phase) of juvenile mutton snapper fed four isonitrogenous and isoenergetic diets with increasing levels of soy protein concentrate (SPC) in substitution to fish meal (FM). The FM was replaced by SPC at 0% (basal diet, SPC000), 33% (SPC130), 57% (SPC214) and 77% (SPC300). After 95 days of rearing, fish fed SPC300 attained a significantly lower body weight (54.9 ± 13.2 g) compared with those fed diets SPC000, SPC130 and SPC214 (76.5 ± 14.0 g, 73.9 ± 13.8 g and 70.5 ± 14.0 g respectively). Fish yield increased significantly from 891 ± 36 g m^?3 for fish fed SPC300 to an average of 1099 ± 111 g m^?3 for other diets. A maximum fish body weight gain of 0.60 ± 0.05 g day^?1 and a maximum specific growth rate of 1.47 ± 0.07% day^?1 were achieved for SPC000. Behavioural assays conducted during 10 days revealed the loss in fish growth with diets containing higher levels of SPC was due to a decline in feed intake. Low feed intake driven by a poor feed palatability appeared to have been a major obstacle against higher inputs of SPC in diets for mutton snapper.