TEA TREE (Melaleuca alternifolia) AND GERANIUM (Pelargonium graveolens) ESSENTIAL OILS AS NEW ANESTHETICS IN RAINBOW TROUT (Oncorhynchus mykiss)

In the present study was investigated anesthetic and histopathological effects of tea tree (Melaleuca alternifolia) and geranium (Pelargonium graveolens) essential oils in rainbow trout. These essential oils were applied at 20, 50, 70, 100, 150, 200, 300, 400, 500 and 600 mg L-1 concentrations to determine the anesthetic effect. As a result of this study, majorcomponents were found as beta-citronellol (27.52%) for geranium oil and 4-terpineol (40.77%)for tea tree oil. The lowest effective doses of geranium and tea tree oils were 400 mg L-1 and300 mg L-1 for deep anesthesia of fish, respectively. At these doses, anesthesia induction andrecovery times were 129.00 and 247.00 s for geranium essential oil, 118.67 and 65s for tea treeessential oil, respectively. No histopathological findings in liver, kidney and gill tissues wereobserved in anesthetized fish for each essential oil. In conclusion, geranium and tea tree oilscan use as safe and effective anesthetics for rainbow trout. Eterična olja čajevca (Melaleuca alternifolia) in pelargonije (Pelargonium graveolens) kot nova anestetika pri šarenki (Oncorhynchus mykiss) Izvleček: Študija je preučevala anestetične in histopatološke učinke eteričnih olj čajevca (Melaleuca alternifolia) in pelargonije (Pelargonium graveolens) na šarenko. Ti eterični olji sta bili uporabljeni v koncentracijah 20, 50, 70, 100, 150, 200, 300, 400, 500 in 600 mg L-1 za določitev anestetičnega učinka. Na podlagi te študije so bile ugotovljene naslednje glavne sestavine: beta-citronelol (27,52 %) za olje geranije in 4-terpineol (40,77 %) za olje čajevca. Najnižji učinkoviti odmerki olja geranije in čajevca so bili 400 mg L-1 oziroma 300 mg L-1 za globoko anestezijo rib. Pri teh odmerkih sta bila čas indukcije anestezije in čas prebujanja iz anestezije 129,00 in 247,00 s za eterično olje geranije ter 118,67 in 65 s za eterično olje čajevca. Pri anesteziranih ribah pri nobenem eteričnem olju niso opazili histopatoloških sprememb v tkivih jeter, ledvic in škrg. Iz tega sledi, da se olji geranije in čajevca lahko uporabljata kot varna in učinkovita anestetika za šarenko. Ključne besede: Oncorhynchus mykiss; anestezija; histopatologija; čajevec; geranija