Efficacy of MS-222 and tobacco extract and their effect on physiological changes in juvenile Sterlet (Acipenser ruthenus)

To investigate the efficacy of tobacco extract and MS-222, comparison of hematological parameters, and biochemical indices under optimum doses, 325 specimen of juvenile Sterlet, Acipenser ruthenus with an average weight of 64.1 ± 3.4 gr and total length of 25.3 ± 0.3 were used. Both losing time of equilibrium and induced time of anesthesia were reduced by increasing the concentrations of these two agents, whereas time of recovery increased. Optimal concentrations were selected as 675 mg/l and 60 mg/l for tobacco extract and MS-222, respectively regarding the time of anesthesia and recovery. There was a significant decrease in hematocrit, hemoglobin, number of red blood cells for all treatments compared to control group; then, significant changes was observed in the mean corpuscular volume, mean corpuscular hemoglobin. Also, white blood cells, neutrophil, lymphosyte, and eosinophil changed significantly among treatments. A significant increase in plasma cortisol was observed immediately after induction for all treatments, then decreased from start to the end. Whereas, only fish exposed to handling stress indicated significant change in glucose concentration. On the other hand, lactate concentration indicated a significant decrease trend for both tobacco extract and handling stress, which the maximum level occurred immediately after induction. Overall, considering the lower changes in biochemical indices for fish anesthetized with MS-222 compared to tobacco extract, it appears MS-222 had the lower physiological responses in juvenile Sterlet, and therefore would be recommended rather than tobacco extract.