What toxin is found in the tissues of many pufferfish?

Tetrodotoxin is the toxin found in the tissues of many pufferfish.

Tetrodotoxin, commonly abbreviated TTX, blocks voltage-gated sodium channels in nerve and muscle cells. By preventing normal electrical signaling, it can cause numbness, paralysis and potentially fatal respiratory failure. It is an extremely potent neurotoxin, and there is no widely available antidote used in routine treatment.

Pufferfish do not necessarily manufacture all of their tetrodotoxin themselves. In many cases, the toxin is associated with bacteria and enters the animal through its food web. Concentrations can vary greatly among species, individuals, organs and geographic populations. The liver, ovaries, intestines and skin may contain especially high levels.

In Japan, carefully prepared pufferfish is known as fugu. Only specially trained and licensed chefs may prepare it, and regulations are designed to reduce poisoning risk. Cooking does not reliably make tetrodotoxin safe. The toxin’s name comes from Tetraodontidae, the pufferfish family, rather than from the word “toxic.”