Effects of anesthesia and salt treatment on stress responses, and immunological and hydromineral characteristics of common carp (Cyprinus carpio, Linnaeus, 1758) subjected to transportation

The aim of the present study was to investigate the effects of anesthesia or salt treatment on stress responses, and immunological and hydromineral characteristics of common carp (Cyprinus carpio). The fish were either transported (5 h) either directly (control), following anesthesia (AN) or with salt addition to transportation tank water (SLT). Transportation was carried out in plastic bags supplied with pure oxygen. The control fish were directly transferred from a holding aquarium to the transportation bags. The fish of AN group were first anesthetized (100 mg/L eugenol for 90 s) in their holding aquaria, then transferred to the transportation bags. The fish of the SLT group were directly transferred to the transportation bags containing 3 g/L salt. Blood samples were taken before and 0, 1, 2 and 3 days after the 5-h transportation. Results showed that salt treatment mitigated decrease in water pH and dissolved oxygen and increase in water ammonia levels. Transportation led to increase in serum cortisol, glucose and calcium levels, and decrease in serum lactate, sodium, chloride, lysozyme, alternative complement (ACH50) and total immunoglobulin (Ig). Salt treatment mitigated stress responses and inhibited hydromineral disturbance and immunosuppression after transportation. Pre-transportation anesthesia negligibly counteracted the adverse effects of transportation on water unionized ammonia, and serum chloride levels. In conclusion, addition of 3 g/L salt to transportation water seems to be beneficial for common carp as it mitigates water quality deterioration, stress responses, hydromineral imbalance and immunosuppression.