Comparison of Hematological Parameters in Rainbow Trout (Oncorhynchus mykiss) Anesthetized with Myrcene and Eugenol

Myrcene is a compound found in many plants with beneficial health effects. Anesthetic efficacy of myrcene has been demonstrated in fish; however, there is no information about its effects on hematological effects. The aim of the present study was to investigate the effects of anesthesia with myrcene on hematological parameters of rainbow trout in comparison to eugenol. In this study, 240 rainbow trout (300 g) were used. The fish were anesthetized within 60, 180, 300 and 600 s with either myrcene or eugenol. To reach these time on anesthesia, 81, 30, 19 and 10 mg/L eugenol, or 531, 251, 177 and 111 mg/L myrcene were used. Blood samples were taken from the fish after anesthesia. Hematological parameters including blood cells’ number, leukocyte differential count, hemoglobin, hematocrit, MCV, MCH and MCHC were determined and compared among the treatments. Increase in anesthesia time of either eugenol or myrcene led to significant increase in hemoglobin and RBC, and the lowest value was related to 60 s. Among the myrcene treatments, increase in induction time results in a significant decrease in WBC and there was a significant difference between 60 and 600 s. Nevertheless, there was no significant difference in leukocyte differential count, MCV, MCH and MCHC among the treatments. Overall, it is concluded that increase in the time of anesthesia with eugenol and myrcene leads to increase in RBC and hemoglobin, which might be an indication of stress. In addition, it seems that anesthesia with myrcene and eugenol within 60-600 s has no certain side effects on the fish.