Anatomical distribution and seasonal variation of toxicity of puffer fish,"Hoshifugu" Arothron firmamentum specimens collected from the Bungo Channel, Oita

Forty-nine specimens of "Hoshifugu" puffer Fish, Arothron firmamentum (23 m ale and 26 female specimens) were collected from the Bungo Channel, Oita Pr efecture, during 1991 to 1997, and examined for the anatomical distribution and the seasonal variation of toxicity by the mouse assay method. Skin showed a rather low level of toxicity and the frequency of toxic speci mens was 6.1% with the maximal lethal potency of 29 mouse unit (MU)/g. Ovar y showed a higher level of toxicity (frequency 80.8%) with the maximal leth al potency of 640 MU/g. On the other hand, the muscle, liver, testis and in testine were non-toxic. Ovaries collected in 6 different months (March, May , and August-November) were found to be toxic with the frequency of 50 simi lar to 100%. Skins were found to be toxic in August and October. It appears that this species has high toxicity in the ovary during early summer to au tumn. Since the muscle of "Hoshifugu" puffer Ash specimens caught in the Bungo Ch annel was non-toxic, the muscle of this species appears to be edible withou t risk to humans.