Effects of different dietary levels of L-ascorbic acid on growth and tissue vitamin C concentration in juvenile Korean rockfish, Sebastes schlegeli (Hilgendorf)

The effects of dietary levels of L-ascorbic acid (AA) on growth and tissue concentration in juvenile Korean rockfish, Sebastes schlegeli (Hilgendorf), were studied, After a 1 week conditioning period, the fish were divided into six groups and given a semipurified diet for 16 weeks, Experimental diets were supplemented with either 0, 25, 50, 75, 150 or 1500 mg L-AA kg(-1) diet (C-0, C-25, C-50, C-75, C-150 and C-1500). Fish fed C-0-C-75 diets showed lower weight gain (WG), feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER) and condition factor than fish fed the C-1500 diet (P < 0.05), Fish fed the Co diet showed vitamin C deficiency symptoms such as scoliosis, exophthalmia and fin haemorrhage after 12 weeks, After 16 weeks of the experiment, the brain ascorbic acid (AA) concentrations of the fish fed C-0-C-75 diets were lower than those of fish fed the C-150 and C-1500 diets (P < 0.05). The muscle and liver AA concentrations of fish fed the C-0 diet were lower than those of fish fed the C-150 and C-1500 diets (P < 0.05). Broken line analyses for WG, FCR, SGR and FER showed that the optimum levels of vitamin C were 102, 100, 103 and 102 mg AA kg(-1) diet, respectively. These findings suggest that dietary levels greater than at least 103 mg AA are required for maximum growth and levels greater than at least 1390 mg AA kg(-1) diet for vitamin C saturation in the tissues of juvenile Korean rockfish.