Effect of 2-phenoxyethanol anesthesia on some haematological and biochemical indices of silver carp (Hypophthalmichthysmolitrix)

In this study, the anesthetic effects of 2-phenoxyethanol (2-PE) on possible primary (cortisol level) and secondary (haematological indices and glucose level) stress responses were studied in silver carp (Hypophthalmichthys molitrix). Fish were first exposed to 0.1, 0.3, 0.5, 0.7 and 0.9 mL/L 2-PE, also the time to induction (deep anesthesia) and recovery were measured. At concentrations of 0.5, 0.7 and 0.9 mL/L, all fish were anaesthetized within 3 min of exposure. For assessing possible stress effects caused by effective concentrations of 2-PE, the haematological indices, serum cortisol and glucose were determined in the deeply anaesthetized fish as stress indicators. 2-PE exposure resulted in a significant increase in red blood cell (RBC) amounts at 0.1 and 0.3 mL/L. It was observed a parallel increase in hemoglobin and Haematocrite amounts at 0.1 concentrations (P < 0.05). The serum cortisol levels had the highest amount in 0.1 mL/L of 2-PE. Moreover 2-PE exposure resulted in a significant increase in glucose amounts at the first 0.1 then 0.3 mL/L concentrations. This study shows that rapid induction of deep anesthesia with a relatively high concentration of 2-PE (0.5, 0.7 and 0.9 mL/L) was connected with the lowest effects on the haematological and serum biochemical indices in silver carp and so 0.7 mL/L could be suggested as suitable doses for haematological studies in this species.