Improvement of common carp (Cyprinus carpio) fingerlings resistance to salinity stress with dietary safflower (Carthamus tinctorius L) extract supplementation

In this study, the effect of dietary safflower extract supplementation was investigated on common carp survival and physiological response to salinity stress. To this, the fingerling fish with average weight of 9.51 ± 0/13 g were fed with diets containing 0, 0.5, 1.5 and 3 % safflower extract for 70 days. After this period, some fish were randomly exposed to water salinity of 20 g/l and their mortality was recorded for 10 h. Also, the remaining fish were exposed to water salinity of 14 g/l and their serum biochemical parameters were monitored for 72 h. Results showed that safflower extract had no significant effect on fish growth. After exposure to 20 g/l salinity, mortality in the control fish reached 100 %, but mortality of 0.5-3% safflower extract groups was 35-50%. After exposure to 14 g/l salinity, serum cortisol and glucose increased and the increment was higher in the control treatment. Also, salinity exposure increased serum sodium and chloride in all of studied groups but there was no significant difference among the treatments. After salinity challenge, serum chloride increased in the control treatment, but in chloride levels of safflower extract no change were recorded. Overall, the results of this study showed that addition of 0.5 - 3 % safflower extract to common carp diet increased resistance to salinity challenge and mitigated stress.