Myrcene and linalool as new anesthetic and sedative agents in common carp, Cyprinus carpio - Comparison with eugenol

The aim of this study was to investigate anesthetic efficacy of myrcene and linalool on Cyprinus carpio in comparison with eugenol. The fish were exposed to 150, 200, 400, 600, 800, 1000 and 1200ppm myrcene, 200, 400, 600, 800, 1000, 1200, 1400 and 1600ppm linalool, and 25, 35, 50, 75, 100, 150 and 200ppm eugenol and induction time were recorded based on fish behaviors. Exposure of the fish to 150–1000ppm myrcene led to 594–42.7s induction time with no significant difference between 1000 and 1200ppm. Recovery at 150–800ppm myrcene occurred within 149–272s with no significant difference among 800–1200ppm. Exposure to 200–1400ppm linalool resulted in 812–79s induction time, with no significant difference between 1400 and 1600ppm. There was no significant difference in recovery time at different linalool concentrations (150–165s). Induction time in both anesthetics were significantly dependent on anesthetic concentrations (R2=0.94–0.96). Recovery time in the myrcene-exposed fish was dependent on anesthetic concentrations (R2=0.77). Using regression models, calculated myrcene concentrations to induce stage 4 anesthesia within 60 and 180s were 819 and 350ppm. Required linalool concentration to induce stage 4 anesthesia within 180s was calculated to be 753ppm. Myrcene at 50ppm and linalool at 50 and 100ppm are able to keep the fish at stage 2 anesthesia for 2h. This study showed for the first time that linalool and myrcene are potential anesthetic in carp, although not as efficacious as eugenol.Anesthetics are used in many aquaculture-related activities. Herbal materials have been considered as alternatives for chemical anesthetics in fish due to their potential health benefits. Myrcene is not studied as anesthetic in fish. Limited data are available on linalool anesthetic efficacy in fish. Therefore, we conducted this study to investigate their potential anesthetic efficacy in carp.