The investigation of effectiveness of mentha piperita and mentha spicata essential oils as anesthetics in rainbow trout (oncorhynchus mykiss)

Anesthetics are widely used in aquaculture. However, some synthetic anesthetics are known to cause side effects in fish. It also causes residues and has negative effects on human health. Therefore, the search for reliable and effective natural products against synthetic anesthetics has increased rapidly. In this study, the anesthetic effects of Mentha piperita and Mentha spicata essential oils on rainbow trout (Oncorhynchus mykiss, Walbaum) were determined by comparing with phenoxyethanol. Rainbow trout with an average weight of 15 g was used in the experiment. In order to determine the anesthetic effect, the essential oils were prepared in concentrations of 50, 100, 200, 300, 500 mg L-1. Anesthesia induction and recovery times were evaluated separately for each fish. In addition, acute toxicity of essential oils on rainbow trout was determined by determination of LC50 concentration in fish exposed to different concentrations of essential oil for 10 minutes. Results showed that induction time decreased with increasing of the concentration of the each essential oil. However, recovery time increased with increasing of the concentration of this anesthetics. 200 mg L-1 dose of M. piperita and M. spicata essential oils provided deep anesthesia on fish. These concentrations were found to be higher in anesthesia induction compared to phenoxy ethanol (287 sec). These times for M. piperita and M. spicata 169.5 and 65 sec respectively. According to acute toxicity test, 10 minutes LC50 concentration (50% death) of both essential oils were 150 mg L-1 . In the light of these findings, it is suggested that fennel and cumin oils can be used as anesthetics in rainbow trout.