tetrodotoxic fishes

those fishes causing tetraodon or puffer poisoning, certain members of the tetraodontiform families Tetraodontidae, Diodontidae, Canthigasteridae, and possible the Molidae and Triodontidae. The toxicity of a species is often subject to variation from specimen to specimen and from one locality to another, some being harmless, others highly toxic. They are generally most toxic immediately preceding and during the height of gonadal activity. Female puffers are considerably more toxic then the male. The skin, liver, ovaries and intestines are the most toxic parts; the musculature is usually safer to eat than other parts but may be at times toxic. Immunity is not gained by repeated ingestion. The poison is not inactivated by cooking