How Do I Know If My Fish Is Contaminated by Ciguatera Toxin?

Ciguatera Fish Poisoning
Since ciguatoxin is odorless and tasteless, as well as harmless to fish, it is not possible to know if a particular fish is contaminated by ciguatera food poisoning.

Ciguatera fish poisoning (ciguatera food poisoning or ciguatera poisoning) is a seafood-borne illness caused by consuming contaminated reef fish that contain a toxin called ciguatoxin, which is poisonous to humans. When ingested, the toxin produces numerous gastrointestinal, muscular, neurological and cardiovascular symptoms, which last for days to weeks or even months.

Ciguatera toxin is harmless to fish who often appear healthy when contaminated by it. Hence, it is not possible to know if a fish has ciguatera. The toxin is odorless and tasteless and cannot be destroyed by cooking, smoking, freezing, salting or any other method of food preparation.

Ciguatera food poisoning commonly occurs in tropical and subtropical areas, particularly in the Pacific Ocean, Indian Ocean and the Caribbean Sea. Outbreaks may occur seasonally or occasionally after storms. One of the most common causes of toxicity, consumption of imported fish from the tropical and subtropical regions, as well as tourism, has now made ciguatera fish poisoning a worldwide health concern that has been known for centuries.

What causes ciguatera fish poisoning?

Ciguatera fish poisoning is caused by the consumption of reef fish that contain accumulated ciguatoxins. These toxins are produced by dinoflagellates, which are small marine organisms (microalgae) that belong to the species Gambierdiscus toxicus. Typically, they live in the coral reefs in tropical or subtropical areas.

Small herbivorous fish feed on these dinoflagellates. The ciguatoxins bio-accumulate in the marine food chain and contaminate larger predatory fish, usually weighing over 6 lbs. When humans consume the contaminated fish, it causes ciguatera fish poisoning.

Fish at risk of ciguatera food poisoning

More than 400 different species of fish have been associated as the cause of ciguatera fish poisoning and such fish are said to be ciguatoxic fish. Ciguatera toxin may be found in any large reef fish but is mostly found in barracuda, grouper, red snapper, moray eel amberjack, perch Spanish mackerel, parrotfish, hogfish, sturgeon fish, kingfish, coral trout and sea bass.

What are the signs and symptoms of ciguatera fish poisoning?

Symptoms of ciguatera food poisoning generally begin six to eight hours after eating the contaminated fish, and may include:

  • Gastrointestinal symptoms: Characterize the first stage of ciguatera poisoning and appear within 12 hours of consuming the contaminated fish, lasting for a couple of days.
  • Neurological symptoms: The next set of symptoms affects the neurological system. These symptoms can appear in a few hours or several days after consumption of the contaminated fish and may continue for several months.
  • Cardiovascular symptoms: The third set of symptoms affects the cardiovascular system.
  • Cold allodynia: A characteristic symptom of ciguatera food poisoning is cold allodynia, which is a dysesthesia (unpleasant, abnormal sensation) that induces a burning sensation when in contact with cold objects.

Severe cases of ciguatera poisoning may result in breathing difficulties, muscular paralysis, coma, itching, skin rash, stiff neck, sweating, chills, tearing of the eyes or drooling.

Death due to heart or respiratory failure may occur in rare cases within 24 hours.


According to the USDA, there is no difference between a “portion” and a “serving.” See Answer

How is ciguatera fish poisoning treated?

Immediate medical attention is necessary for ciguatera food poisoning since the symptoms can rapidly progress in certain patients, and may include gastric lavage in severe cases.

There is no specific antidote for ciguatera poisoning. However, the mainstay of treatment is supportive care, such as:

Consumption of alcohol, fish, nuts and nut oils should be avoided after ciguatera poisoning because these may cause recurrent symptoms.

Prevention of ciguatera fish poisoning

Ciguatera food poisoning may be prevented by:

  • Avoiding eating reef fish that weighs 6 lbs or more.
  • Avoiding eating the liver, intestine, head and roe of smaller reef fish.
Centers for Disease Control and Prevention. Fish Poisoning in Travelers: Ciguatera and Scombroid.

Friedman MA, Fleming LE, Fernandez M, et al. Ciguatera Fish Poisoning: Treatment, Prevention and Management. Mar Drugs. 2008;6(3):456-479.

Science Direct. Ciguatera.

National Organization for Rare Disorders. Ciguatera Fish Poisoning.