Cortisol and hematological response in Brazilian codling, Urophycis brasiliensis (Pisces, Phycidae) subjected to anesthetic treatment

The effects of benzocaine anesthesia on hematological parameters (erythrocyte and platelet number, hemoglobin concentration and hematocrit), plasma electrolytes (Na+, K+ and Cl-), cortisol, glucose and cholesterol levels in Brazilian codling (Urophycis brasilensis) exposed to a benzocaine bath solution were investigated. Cortisol and glucose levels 1 h after capture from the wild and on days 7 and 14 during the acclimatization period (20 days) were also determined. During the second week, cortisol levels reached to basal values (9 ng ml(-1)). The use of benzocaine causes a significant increase in the erythrocyte number, in the concentration of hemoglobin and sodium and a decrease in chloride. Plasma cortisol and cholesterol levels were higher in fish exposed to the anesthetic, and glucose levels decreased significantly comparing with the control group, showing strong fluctuations between individuals in all the cases. These results show that the use of benzocaine causes an acute stress response that could be reverted quickly and it has to be considered during the evaluation of stress in fish.