Comparison of Toxicity of Two Pufferfish, Fugu rubripes chinensis (“Karasu”) and Fugu rubripes rubripes (“Torafugu”)

The toxicity levels of the livers and ovaries of 66 specimens (40 males, 26 females) of pufferfish, Fugu rubripes chinensis (“karasu”), were assayed and compared with those of F. rubripes rubripes (“torafugu”) specimens. The karasu males had a toxic liver frequency of 15.0% with the highest toxicity score of 100MU/g, whereas the females showed a toxic liver frequency of 23.1% and the highest toxicity of 1, 500MU/g. In the case of torafugu, the toxic liver frequency and the highest toxicity were 9.5% and 100MU/g, respectively, for males, and 21.7% and 510MU/g, respectively, for females. On the other hand, the toxic ovary frequency was 57.7% and the highest toxicity was 2, 000MU/g in karasu, and the corresponding values were 65.2% and 820MU/g in torafugu.It follows therefore that females are more toxic than males in both species, that the average toxicity of karasu is roughly comparable to that of torafugu, and that the livers are sometimes toxic enough to kill a man even when ingested in a small amount.