| Abstract: | The effects of clove oil anaesthetic on mitigating the physiological responses to air exposure, a stressful and routine situation in fish farming, laboratory conditions and sport fishing (catch and release), were evaluated in lambari (A. altiparanae). Adult females (n = 80) were randomly sorted to receive one of four treatments: control, anaesthesia (clove oil 50 mg/L), stress (5 min air exposure) and pre‐anaesthesia associated to stress. Their cortisol, glucose, lactate and haematocrit levels, the hepatosomatic index (HSI), liver and muscle glycogen, lipid peroxidation and the enzymatic activity of lactate dehydrogenase (LDH), catalase (CAT) and glutathione reductase (GR), were recorded. Glucose levels increased (53.9%) after anaesthesia and/or stress. The stress situation increased plasma cortisol (146.6%), lactate (294.6%) and lipid peroxidation in white muscle (45%) and decreased glycogen in white muscle (40.1%). The haematocrit increased after stress or anaesthesia (7.9%) while the liver glycogen and HSI did not change. Anaesthesia or stress did not affect the LDH but reduced the activity of CAT (46.1%) and GR (30.3%). We concluded that the anaesthetic clove oil in the concentration 50 mg/L modulates the physiological responses to air exposure stress improving the welfare; air exposure and clove oil affect the antioxidant defences of lambari; the activity of CAT and GR and the concentration of MDA can be used as biomarkers of stress in A. altiparanae. |
