Comparison of the effects of four anaesthetics on blood biochemical profiles and oxidative stress biomarkers in rainbow trout

Abstract

The feasibility of using clove oil, 2-phenoxyethanol, or Propiscin as an alternative to tricaine methane sulphonate (MS 222) for anaesthetizing fish was studied, particularly with respect to reducing stress. The blood biochemical and antioxidant profiles of rainbow trout Oncorhynchus mykiss anaesthetized with MS 222 (100 mg l − 1 ), clove oil (30 mg l − 1 ), 2-phenoxyethanol (0.40 ml l − 1 ), or Propiscin (1.0 ml l − 1 ), and a non-anaesthetized control group, were compared. Biochemical and antioxidant profiles were determined from blood samples collected prior to treatment in controls. For each anaesthetic tested, fish were divided into two groups, one sampled immediately after 10 min anaesthesia and a second, sampled 24 h after 10 min anaesthesia. Our results suggest that internal organs and tissues of rainbow trout were slightly altered by all tested anaesthetics and resulted in increased reactive oxygen species formation, leading to oxidative damage to lipids and proteins and inhibition of antioxidant capacities. In short, a low level of oxidative stress could induce the adaptive responses of antioxidant enzymes. On the basis of this experiment, it appears that Propiscin was associated with the lowest effects in rainbow trout and therefore would be recommended as an alternative to MS 222.