Effect of adding salt and Bacillus subtilis to diet on cortisol response and antioxidant indices of wild common carp fry, Cyprinus carpio under salinity stress

This research was conducted in order to investigate the effect of adding salt and Bacillus subtilis bacteria (IS02) to the diet on the survival, cortisol response and antioxidant indices of sea carp, Cyprinus carpio, under salinity stress. Baby carp fish (average 1.1 g) were fed with diets containing 5 and 10% salt or 108 x 5.2 and 109 x 5.2 colony grams (cfu/g) of probiotics for 15 days and then to They were directly transferred to saline water with a concentration of 13 grams per liter and samples were taken after 3 and 10 days. Survival in all treatments was above 96%. The amount of cortisol at baseline and after salinity stress in probiotic treatments was significantly lower than other treatments. Superoxide dismutase activity was higher in probiotic treatments than other treatments. Diets had no significant effect on catalase activity. Based on the results of this research, the use of B. subtilis in the diet can reduce stress and increase the antioxidant capacity in juvenile Norse carp.