Efficiency of thyme (Origanum onites) and coriander (Coriandrum sativum) essential oils on anesthesia and histopathology of rainbow trout (Oncorhynchus mykiss)

Abstract

The aim of this study was to investigate the anesthetic efficiency of coriander (Coriandrum sativum) and thyme (Origanum onites) essential oils at different concentrations (20, 50, 70, 100, 150, 200, 300, 400, 500, 600 mg L−1) on rainbow trout (Oncorhynchus mykiss). Additionally, the histopathological effects of essential oils were investigated on the fish tissues including gill, liver and kidney. At the end of the experiment, coriander essential oil was observed to be sedative at 50 mg L−1 and had an anesthetic effect at a concentration of 200 mg L−1 in rainbow trout. However, thyme essential oil caused mortality at the tested concentrations in rainbow trout. Histopathological examination, hyperemia, edema and desquamation were observed in the thyme group’ gills. Also, liver and kidney hyperemia was noticed in this group. No pathological findings were observed in any organ of fishes in the coriander group. The present study demonstrated that concentrations of 200 mg L−1 coriander essential oil can be used as an anesthetic for rainbow trout.