sensory nerve. Tetrodotoxin mainly acts on the peripheral nerve and the central nerve of the brain stem, causing paralysis in essence, first causing peripheral sensory nerve paralysis, then motor nerve paralysis, and finally involving the brain stem and the center. ECG examination shows that most patients have different degrees of cardiac conduction system block, and the more severe the poisoning, the more serious the ECG changes. Tetrodotoxin is a strong neurotoxin, which mainly exists in the liver, ovary and skin of puffer fish.