Effect of carbon dioxide anesthesia on physiology and quality of tilapia

We used carbon dioxide (CO₂) to anesthetize tilapia (Oreochromis niloticus) to reduce the stress response caused by operation, and analyzed the changes of physiology and meat quality of tilapia during anesthesia and resuscitation. By studying the anesthetic effects of different treatment temperatures, we found that the optimal temperature for CO₂ anesthesia of tilapia was 15 ℃; the duration of anesthesia was (101±18) s; the duration of resuscitation was (134±23) s. The serum indexes of hydrocortisone (COR), blood glucose (GLU), aspartate aminotransferase (AST),  alanine aminotransferase (ALT) and alkaline phosphatase (ALP) increased significantly after anesthesia, but decreased after resuscitation. The glycogen (GLY) content decreased significantly after anesthesia, while the lactic acid (LD) content in liver reached the maximum value after resuscitation. The LD content in muscle increased during anesthesia but decreased when the stress was relieved. High malondialdehyde (MDA) content but low superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC)  activity were observed during anesthesia. The hardness, adhesiveness and chewiness of the fillets were significantly affected by anesthesia, but could recover to the control group's level after 24 h, with stable flexibility. In conclusion, tilapia can be anesthetized effectively and quickly after CO₂ anesthesia treatment; anesthesia treatment causes oxidative stress response of tilapia; and the physiological state of tilapia can be restored after stress was relieved.