Fish and Shellfish Poisoning
At certain times of the year, various species of fish and shellfish contain poisonous
biotoxins, even if well cooked. According to the CDC, it is considered an under-recognized
risk for travelers, specifically in the tropics and subtropics.
Certain fish—groupers, barracudas, moray eel, sturgeon, sea bass, red snapper, amberjack, mackerel,
parrot fish, surgeonfish, and triggerfish—can cause ciguatera fish poisoning. 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 poisoning or fugu poisoning, and 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 United States 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 United States.
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 generally appear between a few minutes and 6 hours
after the toxic fish has been eaten. These include a variety of gastrointestinal,
neurological, and cardiovascular abnormalities. The following are the most common
symptoms of ciguatera poisoning. However, each individual may experience symptoms
differently. Symptoms may include:
In more severe cases, the person may suffer muscle pains, dizziness, and sensations
of temperature reversal, where hot things seem cold and cold things seem hot. Irregular
heart rhythms and low blood pressure may also be experienced. Ciguatera poisoning
symptoms typically resolve within several days, but may last up to 4 weeks. The symptoms
of ciguatera poisoning may resemble other medical conditions. Always talk with your
healthcare provider for a diagnosis.
Treatment for ciguatera poisoning
Treatment for ciguatera poisoning involves relieving 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, also called pufferfish poisoning or fugu poisoning, is a much rarer
form of fish poisoning. Yet, it is potentially very serious. This is almost exclusively
associated with eating the pufferfish from waters of the Indo-Pacific regions. There
have also been several reported cases of poisonings, including fatalities, 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 generally appear between 20 minutes and 3 hours after eating the poisonous
pufferfish. The following are the most common symptoms of pufferfish poisoning. However,
each individual may experience symptoms differently. Symptoms may include:
Numbness of lips and tongue
Numbness of face and extremities
Sensations of lightness or floating
Nausea and vomiting
Extensive muscle weakness
Death can happen within 4 to 6 hours of poisoning. It is essential to seek immediate
Treatment for pufferfish poisoning
Treatment for pufferfish poisoning consists of limiting the body's absorption of the
toxin, relieving symptoms, and treating life-threatening complications. There is no
known antidote for tetrodotoxin.
What is scombrotoxin?
Scombrotoxin, also called scombroid poisoning or histamine poisoning, happens after
eating fish that contain high levels of histamine due to improper food handling. It
remains one of the most common forms of fish poisoning in the U.S. and worldwide. These
fish, which include mahi mahi (dolphin fish), albacore tuna, bluefin and yellowfin
tuna, bluefish, mackerel, sardines, anchovy, herring, marlin, amberjack, and abalone,
have high amounts of histidine. As a result of inadequate refrigeration or preservation,
bacteria convert the histidine to histamine. This leads to scombroid poisoning. Contaminated
fish may appear and taste fresh, although some may taste "peppery," "spicy," or "bubbly."
The toxin may form even if the fish has only been temporarily stored at too high a
This form of fish poisoning happens worldwide in temperate and tropical waters.
What are the symptoms of scombroid poisoning?
Symptoms generally appear within minutes to an hour after eating affected fish. They
typically last 3 hours, but can last several days. The following are the most common
symptoms of scombroid poisoning. However, each individual may experience symptoms
differently. Symptoms may include:
Tingling or burning sensations in the mouth
Rash on the face and upper body
Wheezing or shortness of breath
Drop in blood pressure
Hives and itching of skin
The symptoms of scombroid poisoning may resemble other medical 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 unnecessary. Symptoms usually resolve
within 12 hours and scombroid 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