Fundamental studies for establishing rockfish culture techniques. 6. The protein digesting ability and the favourable contents of protein in diets for the rockfish Sebastes schlegeli
Ikehara, K.; Nagahara, M.
Bulletin of the Japan Sea National Fisheries Research Institute 31: 65-72
Digestibility for different size young S. schlegeli under different thermal conditions and the growth rate and food efficiency for uniform size fish at various fish meal contents were studied in the lab. The feces/ration ratio was inversely proportional to fish size. The young fish (body weight 4 g mean) commenced feces excretion 1 or 2 h after feeding at temperatures of 25-26.degree. C. Digestion at temperatures of 10-12.degree. C took twice as long as that at 18-26.degree. C. Digestibility of dietary protein increased with time in the initial 24 h to .apprx. 90%; after that no digestion was observed. They were independent of fish size and temperature. Fish fed on compound feed showed normal growth, but some fed on jack mackerel muscle for 2 mo. got hypovitaminosis or died. The most favorable protein content was estimated at about 41%.