Effects of dietary vitamin C on skeleton abnormalities, blood biochemical factors, haematocrit, growth, survival and stress response of Cyprinus carpio fry

The aim of this study was to assess the effects of vitamin C (vitC) on the growth, skeletal abnormalities (vertebral column and lack of operculum), blood biochemical parameters, haematocrit, survival and resistance to salinity stress in common carp fry (0.5 +/- 0.08 g). Fish were fed diets containing vitC at different levels: 0 (control), 50, 100 and 1000 mg kg(-1) diet for 48 days. The results showed that there was a significant increase in final weight, weight gain and specific growth rate in those fish fed vitC diets compared with the control (P < 0.05). Food conversion rate of fish fed vitC diets was significantly (P < 0.05) lower than the control group. On the other hand, abnormalities in the operculum and vertebral column were found in fish fed the vitC-free diet, but did not significantly different compared with treatment groups (P < 0.05). Challenges were carried out after 48 days of feeding, to determine the effect of vitamin C on resistance to different salinities (0, 6 and 12 ppt). Cortisol, haematocrit (fish fed control diet), sodium, potassium, calcium and magnesium levels increased with the increase in salinity (P < 0.05). Haematocrit levels of fish fed the vitamin C-supplemented diets were not significantly affected by different salinities (P > 0.05). In addition, supplementation of vitC significantly increased survival rate and resistance to salinity stress challenge of fed fish. These results confirm that vitC improves growth performance, skeletal development, blood parameters, survival and resistance to salinity stress of common carp fry, a very important fish species in the Caspian Sea.