Effects of different culture salinities on the growth and muscle quality of grass carp (Ctenopharyngodon idellus)

Grass carp (Ctenopharyngodon idellus) is an economically important farmed fish. This experiment was conducted to study the effects of different culture salinities on the growth and muscle quality of grass carp. We found that salinity of 0 to 5 had no significant effect on the growth of grass carp, but it significantly decreased at salinities above 5. Compared to salinity 0, the protein content of serum was significantly higher at salinities of 3 and 5. However, all serum biochemical compound measured, except glucose and total protein, decreased significantly at salinity 9. Muscle textural properties of grass carp were significantly higher at salinities of 3 and 5 than at 0, 7, and 9. Salinities of 0 to 3 had no significant effect on muscle nutrition of grass carp, but this parameter tended to decrease at salinities above 7. Salinities of 3 and 5 significantly favored muscle growth and expression of collagen-related genes, whereas the opposite was true for salinities of 7 and 9. These results indicated that grass carp grew normally at salinities of 3 and 5, with some improvement in muscle quality, whereas salinities of 7 and 9 had a negative effect on growth and quality. Therefore, appropriate salinity levels can help to improve the muscle quality of grass carp without affecting their growth.