In order to examine whether the innocuous cultured puffer fish, Fugu rubripes rubripes (Japanese name, torafugu), is able to accumulate orally administered tetrodotoxin (TTx) or not, a feeding test was carried out for 20 days using the toxic ovary of puffer fish, its methanol extract, and crystalline TTx, and the toxicity of various tissues was bioassayed.
In the fish of the ovary-feeding group, all the tissues tested were already toxic on the 5th day, and the toxicity of most tissues increased gradually during the experimental period. In the fish of the methanol extract-feeding group, only the liver, skin, spleen, and gall-bladder were toxic on the 5th day, and the other tissues also became toxic after 20 days. However, the toxicity of most samples of this group were remarkably lower than those of the corresponding samples of the ovary-feeding group. In a striking contrast to the above two groups, the TTx-feeding group showed almost no toxicity in all the tissues throughout the experimental period.