Seafood Poisoning: Ciguatera and Scombroid

Health and Disability

Author: Thomas C. Weiss
Published: 2015/06/24 - Updated: 2020/09/17
Contents: Summary - Introduction - Main - Related

Synopsis: Information regarding Ciguatera and Scombroid, types of fish, seafood and shellfish poisoning. No matter how long you cook the seafood you will not be protected from becoming poisoned if you eat fish that is contaminated. You can protect yourself by avoiding fish and seafood caught in and around areas of red tide and by avoiding mussels, clams and oysters during the summer months.



In, 'Ciguatera,' food poisoning, the poisonous ingredient is, 'ciguatoxin,' which is a poison made in small amounts by certain algae and algae-like organisms called, 'dinoflagellates.' Small fish that eat the algae become contaminated. Larger fish eat the smaller, contaminated ones and the poison may build up to a dangerous level, which can make a person ill if they consume the fish. Ciguatoxin is, 'heat-stable,' meaning it does not matter how well you cook your fish. If the fish is contaminated - you will become poisoned.

Main Digest

Ciguatera poisoning usually happens in larger fish from tropical waters. The most popular types of these fish which are eaten include grouper, red snapper and sea bass.

In America, the waters around Hawaii and Florida have the greatest potential for fish that are contaminated. The risk is highest in summer months, or any time a large amount of algae are blooming in the ocean such as during, 'red tides.' A red tide happens when there is a quick increase in the amount of dinoflagellates in the water. Today's transportation; however, means that anyone around the world might be sitting themselves down to a dinner from a fish from contaminated waters.


Scombroid food poisoning results from eating spoiled fish. As with ciguatera, it is listed as a common type of seafood poisoning. Scombroid is most commonly reported with mackerel, tuna, bluefish, mahi-mahi, bonito, sardines, anchovies, and related species of fish that were inadequately refrigerated or preserved after being caught.

In, 'Scombroid,' poisoning, the poisonous ingredient is, 'histamine,' and substances that are similar. Average bacteria on these fish create large amounts of toxin after the fish has died and it is not immediately frozen or refrigerated.

In shellfish poisoning, the poisonous ingredient are toxins made by algae-like organisms called dinoflagellates, which build up in some kinds of seafood. There are a number of different types of shellfish poisoning. The most well known types are:

Scombroid poisoning usually happens in large dark meat fish such as mackerel, tuna, albacore and mahi mahi. Since this poison develops after a fish has been caught and died, where the fish is caught does not truly matter. The main factor is how long the fish sits out prior to being frozen or refrigerated.

As with Ciguatera poisoning, the majority of shellfish poisonings happen in warmer waters. Poisonings; however, have happened as far north as the State of Alaska and quite often in New England. Most shellfish poisonings happen during the summer. You might have heard the saying, 'Never eat seafood in months that do not have the letter R.' The months should include every month from May through August. The number of poisonings also grows when there is a red tide. Shellfish poisonings happen in seafood with two shells such as oysters, clams, scallops and mussels.

Symptoms of Seafood Poisoning

The harmful substances that cause Ciguatera, Scombroid and shellfish poisoning are heat stable. No matter how long you cook the seafood you will not be protected from becoming poisoned if you eat fish that is contaminated. The symptoms depend on the specific type of poisoning a person experiences. Ciguatera poisoning symptoms may occur anywhere from 2-12 hours after a person eats a contaminated fish. The symptoms include the following:

The symptoms of scombroid poisoning often happen promptly after a person consumes a contaminated fish. The symptoms of scombroid poisoning include:

Shellfish Poisoning

There are some different types of shellfish poisoning. What follows are the most well-known types and the symptoms which accompany them.

Treatment of Seafood Poisoning

Shellfish poisoning might be a medical emergency. With sudden or significant symptoms, a person should promptly be taken to an emergency medical center. The person may need to call the local emergency phone number or poison control for proper treatment information.

In an emergency room, a person who is experiencing Ciguatera poisoning may receive some different forms of treatment. The person may receive IV fluids, medication to stop their vomiting, as well as a medication known as, 'Mannitol,' to help reduce neurological symptoms.

If a person is experiencing Scombroid poisoning, they may receive some different forms of treatment in an emergency room. These forms of treatment include:

People who are experiencing shellfish poisoning might receive medication to stop the vomiting, as well as IV fluids to replace lost fluids from vomiting and diarrhea. If shellfish poisoning causes paralysis, the person may have to stay in the hospital until their symptoms improve.


Fish and shellfish poisonings do happen in America. You can protect yourself by avoiding fish and seafood caught in and around areas of red tide and by avoiding mussels, clams and oysters during the summer months. If you are poisoned, your long-term outcome is often quite good.

The symptoms of Scombroid poisoning usually only last for a few hours after medical treatment is started. Ciguatera poisoning and the different shellfish poisoning symptoms might last from days to weeks, depending upon the severity of the poisoning. Only on rare occasion have serious outcomes or death happened.

Due to the fact that these poisons are heat stable, there is no way for the person who prepares someone's food to be aware that their food is contaminated. Because of this fact, it is very important that your doctor tell the restaurant that their food is contaminated so they may throw it out before other people become ill. Your doctor should also contact the Department of Health to ensure the suppliers providing contaminated fish are identified and all potentially contaminated fish from the same lot are destroyed.

Mercury Levels in Fish: Species Chart and Information - A list of low and high mercury concentration levels in fish, includes chart of fish species safe and not safe for pregnant women and the public to eat.

Author Credentials:

Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a Nursing Assistant Thomas has assisted people from a variety of racial, religious, gender, class, and age groups by providing care for people with all forms of disabilities from Multiple Sclerosis to Parkinson's; para and quadriplegia to Spina Bifida. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.

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Cite This Page (APA): Weiss, T. C. (2015, June 24 - Last revised: 2020, September 17). Seafood Poisoning: Ciguatera and Scombroid. Disabled World. Retrieved July 14, 2024 from

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