Understanding of the stress responses in fish may help to improve management, production, and animal welfare. To determine the threshold levels of stress responses in Persian sturgeon, Acipenser persicus, the main indicators of stress (cortisol and glucose) were measured during surgery operation. For this purpose, five blood samples were collected as follow: four samples with 15 min intervals during 45 min surgery and last sampling 24 h after surgery operation. The concentration of cortisol increased rapidly and reached to maximum levels (676.3±37.8 ng/ml) at the time of last sampling that is, 24 h after surgery operation. The plasma glucose levels increased slowly during 15 to 30 min after the beginning of the experiment and reached a maximum level (10.6±1.5 mMol/L) at the time of last blood sampling. Our results show that surgery acts as a very severe stressor which adverse impacts remain for a log period after operation. Thus, attention to fish health in relation to rearing conditions will be an essential strategy for female Persian sturgeon after surgery.
