Investigation of anesthetic efficiency of citronella (Cymbopogon winterianus) and palmarosa (Cymbopogon martinii) essential oils on rainbow trout (Oncorhynchus mykiss)

In the present study was investigated anesthetic and histopathological effects of citronella (Cymbopogon winterianus) and palmarosa (Cymbopogon martinii) essential oils in rainbow trout (Oncorhynchus mykiss). Fish with a mean weight of 50 g were used in the experiment. Both essential oils were prepared at different concentrations (25, 50, 75, 100 and 200 mg L-1) to determine the anesthetic effect. Anesthesia induction and recovery times were evaluated for each fish. Then, the histopathological effects on fish tissues of essential oils at anesthetically effective concentration were examined. As a result of this study, major component was found as geraniol for citronella (57.84%) and palmarosa oil (82.23%). In generally, anesthesia induction time of fish decreased with increasing of the concentration of the citronella and palmarosa oil. However, recovery time increased with increasing of the concentration of this anesthetics. The lowest effective doses of citronella and palmarosa were 50 mg L-1 for deep anesthesia (Stage 4) in fish. At these dose, anesthesia induction and recovery times were 203.33 and 123.67 s for citronella essential oil, 184.33 and 61.67s for palmarosa essential oil, respectively. No histopathological findings in gill, skin and liver tissues were observed in anesthetized fish. In the light of these findings, it was determined that citronella and palmarosa oils can be used as safely effective natural anesthetic for rainbow trout.