Tetrodotoxin (TTX) is a neural toxin which was commonly found in marine puffer fish genus of Lagocephalus. It could be applied in medicinal industry, which can be used in pain reducing in cancerous patient. In this study, tissues collected from Lagocephalus have been soaked in different buffers as NaCl, KH2PO4 and distilled water at 37oC in 24 hours. These samples were, then, injected into mice by intraperitonial injection and observed the nervous disorder symptoms. Mice that showed typical nervous symptoms and death had been recorded and analyzed. The tissue samples in different buffer were incubated and then heated at 105oC. These samples were also tested for bioassay in mice. All the symptoms and mice death were analyzed. The results pointed that toxicity in mice due to microorganism in tissues of Lagocephalus