Effects of anaesthesia with 1,8-cineole on haematological and plasma stress responses in Caspian trout, Salmo caspius, subadults

Anaesthesia is an indispensable practice in aquaculture, facilitating fish handling, but it may affect the fish physiological status. Therefore, researches are progressing to find new anaesthetics in fish. 1,8-Cineole (cineole) has been known as anaesthetic in aquaculture, but its anaesthetic and biochemical effects have been tested in a few species. So it is necessary to test cineole anaesthesia effects in other species. In the present study, the effects of different concentrations of cineole on haematological indices, biochemical and stress responses were investigated in Caspian trout, Salmo caspius. The fish were exposed to 50, 200, 400 and 800 ppm cineole within 180, 10, 3 and 1.5 minutes, respectively. Blood samples were taken from the anaesthetized fish as well as non-anaesthetized fish to determine haematological and biochemical parameters: plasma uric acid (p = 0.957), creatinine (p = 0.952), phosphorus (p = 0.543), and calcium (p = 0.797) levels, blood mean corpuscular volume (p = 0.105) and mean corpuscular haemoglobin (p = 0.060). There were no significant differences in the haematological and biochemical parameters between the non-anaesthetized fish and 800 ppm treatments (p > 0.05). Decrease in cineole concentration resulted in elevations in red blood cell, haematocrit, haemoglobin, mean corpuscular haemoglobin concentration, white blood cell, cortisol, glucose, lactate, lactate dehydrogenase and T-4 and decrease in T-3 (p < 0.001). In conclusion, anaesthesia with 800 ppm cineole prevents stress responses in Caspian trout. However, decrease in cineole concentration induces stress and hypoxia, which might be due to longer time of induction.