Tetrodotoxin

From Microcosm Aquarium Explorer

476

"Striped Globe-Fish Puffer," illustration by Bloch, circa 1790. Marcus Elieser Bloch

Don't Eat the Puffer

Puffer enthusiasts often form affectionate bonds with their big-eyed charges, but there is a sinister side to the Family Tetraodontidae that makes them all the more fascinating to many aquarists and divers.

A potent neurotoxin found in the skin and internal organs of pufferfishes (Family Tetraodontidae, tetrodotoxin is responsible for dozens of poisonings and up to six human deaths per year in Japan, where puffer flesh (fugu) is a highly regarded delicacy for certain risk-loving sushi eaters.

Aquarists who do not consume their pet puffers are in no danger from the toxin, but those who ingest it begin to suffer the following symptoms within 10 to 45 minutes: "lightheadedness, vertigo, feelings of doom, weakness, hypersalivation, muscle twitching, diaphoresis, pleuritic chest pain, dysphagia, aphonia, convulsions, hypotension, bradycardia, depressed corneal reflexes, and fixed dilated pupils," according to the McGraw-Hill Concise Dictionary of Modern Medicine.

Fugu puffers in Tokyo fish market. Image by Chris 73/GNU

Death usually comes from respiratory failure caused by paralysis of the diaphragm. In cases where a person has consumed a non-lethal dose, the victim may spend several days in a conscious but "near-death" state.

Zombie Potion?

Harvard ethnobotanist Wade Davis wrote a paper in 1983 suggesting that tetrodotoxin could be an ingredient in Haitian voodoo rites that turn healthy individuals into zombies. (See his book, The Serpent and the Rainbow, 1985.) Other scientists have both disputed and bolstered his claims, and trace amounts of tetrodotoxin have been identified in so-called "Zombie Powder."

There is no known antidote for tetrodotoxin. (Victims are usually placed on life support systems with special attention to keeping them breathing until the effects of the toxin wear off.)

It is also found in porcupinefish and some triggerfishes, as well as the Ocean Sunfish or Mola. The toxin is actually a product of certain bacteria, including Pseudoalteromonas teraodonis and Vibrio alginolyticus. The Blue-Ringed Octopus and Rough-skinned Newt are also known to carry this toxin. The toxin has also been isolated in parrotfish, toads, starfish, polyclad flatworms, arrow worms, ribbon worms, and xanthid crabs.

The first written record of tetrodotoxin poisoning is found in the logbooks of Capt. James Cook in 1774. His crew became sick after eating pufferfish flesh, but the ships' pigs that were fed the entrails of the puffers were all found dead the next morning.

Warnings to Aquarists

Aquarists are advised to handle all puffers only with rubber gloves (a good rule for all fishes, actually) and to avoid keeping the Blue-Ringed Octopus, which annually causes a number of deaths among Indo-Pacific fisherfolk. It is often imported for the aquarium trade, and experts fear that this tiny invertebrate will eventually claim the life of a livestock seller or hobbyist.

The Fugu Puffer or Japanese Pufferfish is Takifugu rubripes, a species that breeds in the ocean but may also be found in brackish water estuaries.


See: A Puffer Primer