Use of Cymbopogon citratus Essential Oil as an Anesthetic for Pacamã (Lophiosilurus alexandri): Induction and Recovery Times

Essential oils (EOs) have been widely investigated as natural alternatives to synthetic anesthetics due to their sedative and anesthetic properties, making them promising candidates for use in aquaculture. This study evaluated the anesthetic efficacy of the essential oil Cymbopogon citratus (EOCC) in Lophiosilurus alexandri. A total of 80 juveniles (11.29 ± 2.27 g) were subjected to a 24 h fasting period before the experiment. The EOCC concentrations tested were 50, 75, 100, 125, 150, 175, and 200 mg/L. A control treatment consisting of 2 g of ethanol, equivalent to the amount used to dilute the highest EO concentration, was also included. Ten fish were used per treatment. In the control group, fish were monitored for 10 min to simulate the anesthetic induction period and for 5 min to simulate the recovery period. Anesthetic induction was characterized by the loss of equilibrium and responsiveness to external stimuli, whereas recovery was defined as the restoration of these responses. Following recovery, juveniles were returned to their original tanks, and survival was assessed after 24 h. Data were analyzed using regression analysis. No mortality was observed throughout the experiment. EOCC reduced the induction time as concentration increased (P < 0.0001), with values ranging from 471.78 ± 21.02 s to 87.33 ± 19.82 s. In contrast, anesthetic recovery time was not affected by EOCC concentration (P = 0.4378), ranging from 247.00 ± 34.04 s to 248.11 ± 100.92 s. Considering the criteria of achieving anesthetic induction within 3 min and recovery within 5 min, the concentrations of 150, 175, and 200 mg/ L were considered effective. However, 150 mg/ L is recommended as the optimal concentration because it is the lowest concentration capable of meeting the established anesthetic criteria. This study was funded by Dr. Bruno Bello Vicintin in partnership with Rima Industrial S/A.