Fish and Shellfish Poisoning

At certain times of the year, various species of fish and shellfish contain poisonous biotoxins, even if well cooked. The CDC says it is an under-recognized risk for travelers, specifically in the tropics and subtropics. 

Certain fish can cause ciguatera fish poisoning. These include:

  • Grouper

  • Barracuda

  • Moray eel

  • Sturgeon

  • Sea bass

  • Red snapper

  • Amberjack

  • Mackerel

  • Parrot fish

  • Surgeonfish

  • Triggerfish

The CDC recommends never eating moray eel or barracuda. Other types of fish that may contain the toxin at unpredictable times include sea bass and a wide range of tropical reef and warm-water fish. Fish containing these toxins do not look, smell, or taste bad. Cooking, marinating, freezing, or stewing does not destroy the toxin.

The risk of ciguatera poisoning exists in all tropical and subtropical waters of the West Indies, the Pacific Ocean, and the Indian Ocean, where these reef fish are eaten.

Two other forms of poisoning can happen from naturally occurring toxins in fish:

  • Tetrodotoxin, sometimes called pufferfish or fugu poisoning

  • Scombroid poisoning

Where is the risk of ciguatera poisoning the greatest?

Reef fish from the tropical and subtropical waters of the West Indies, the Pacific Ocean, and the Indian Ocean pose the greatest threat. Cases have been reported in the U.S. in Hawaii, Guam, Puerto Rico, U.S. Virgin Islands, and Florida. A few isolated cases of ciguatera poisoning have even been noted along the eastern seaboard of the U.S.

More than 400 species of fish, particularly reef fish, are thought to contain the toxin for ciguatera poisoning.

What are the symptoms of ciguatera poisoning?

Symptoms of ciguatera poisoning often start between a few minutes and 6 hours after eating the toxic fish. These include a variety of gastrointestinal, neurological, and cardiovascular problems. Each person may have different symptoms. But these are the most common symptoms:

  • Nausea

  • Vomiting

  • Watery diarrhea

  • Belly (abdominal) pain

  • Headache

  • Numbness and tingling about the mouth and extremities

  • Tiredness (fatigue)

In more severe cases, you may suffer muscle pains, dizziness, and sensations of temperature reversal, where hot things seem cold and cold things seem hot. You may also have irregular heart rhythms and low blood pressure. 

These symptoms often go away within several days. But they may last up to 4 weeks. They may look like other health conditions. Always talk with your healthcare provider for a diagnosis.

Treatment for ciguatera poisoning

Treatment for ciguatera poisoning involves easing the symptoms and treating any complications. There is no specific antidote for the toxin itself. Generally, recovery takes from several days to several weeks. 

What is tetrodotoxin?

Tetrodotoxin is also called pufferfish poisoning or fugu poisoning. It is a much rarer form of fish poisoning. Yet, it may be very serious. It is almost exclusively linked to eating the pufferfish from waters of the Indo-Pacific regions. There have also been several reported cases of poisonings, including deaths, from pufferfish from the Atlantic Ocean, Gulf of Mexico, and Gulf of California. Pufferfish poisoning is a continuing problem in Japan.

What are the symptoms of pufferfish poisoning?

Symptoms often start between 20 minutes and 3 hours after eating the poisonous pufferfish. Each person may have different symptoms. But these are the most common symptoms:

  • Numbness of lips and tongue

  • Numbness of face and extremities

  • Sensations of lightness or floating

  • Headache

  • Nausea and vomiting

  • Abdominal pain

  • Diarrhea

  • Slurred speech

  • Trouble walking

  • Extensive muscle weakness

  • Convulsions

  • Trouble breathing

  • Mental impairment

  • Irregular heartbeat

Death can happen within 4 to 6 hours of poisoning. It is vital to seek medical care right away.

Treatment for pufferfish poisoning

Treatment for pufferfish poisoning consists of limiting how much of the toxin the body absorbs. It also involves easing symptoms and treating life-threatening complications. There is no known antidote for tetrodotoxin. 

What is scombrotoxin?

Scombrotoxin is also called scombroid poisoning or histamine poisoning. It happens after eating fish that have high levels of histamine due to improper food handling. It is one of the most common forms of fish poisoning in the U.S. and worldwide. 

Certain fish have high amounts of histidine. As a result of poor refrigeration or preservation, bacteria turn the histidine into histamine. This leads to scombroid poisoning. Contaminated fish may look and taste fresh. But some may taste "peppery," "spicy," or "bubbly." The toxin may form even if the fish has been stored at too high a temperature for only a short time. 

This form of fish poisoning happens worldwide in temperate and tropical waters. It can happen after eating:

  • Mahi mahi (dolphin fish)

  • Albacore tuna

  • Bluefin and yellowfin tuna

  • Bluefish

  • Mackerel

  • Sardines

  • Anchovy

  • Herring

  • Marlin

  • Amberjack

  • Abalone

What are the symptoms of scombroid poisoning?

Symptoms often start within minutes to an hour after eating affected fish. They typically last 3 hours. But they can last several days. Each person may have different symptoms. But the most common symptoms are:

  • Tingling or burning sensations in the mouth

  • Rash on the face and upper body

  • Wheezing or shortness of breath

  • Drop in blood pressure

  • Throbbing headache

  • Hives and itching of skin

  • Nausea

  • Vomiting

  • Diarrhea

These may look like other health conditions. Many cases of "fish allergy" are actually scombroid poisoning. Always talk with your healthcare provider for a diagnosis. 

Treatment for scombroid poisoning

Treatment for scombroid poisoning is generally not needed. Symptoms often go away within 12 hours. This poisoning is rarely life-threatening. Treatment could include antihistamines, such as diphenhydramine and cimetidine.

Specific treatment for all fish and shellfish poisoning is based on:

  • Your overall health and medical history

  • Extent of the disease

  • Your tolerance for specific medicines, procedures, and therapies

  • Your opinion or preference

Online Medical Reviewer: Barry Zingman MD
Online Medical Reviewer: L Renee Watson MSN RN
Online Medical Reviewer: Raymond Turley Jr PA-C
Date Last Reviewed: 5/1/2021
© 2000-2023 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.