Ciguatera in Reef Fish: To Eat or Not To Eat?

To avoid ciguatera know what kind of fish you are buying and where it was caught. Photo by Devi Sharp

Lionfish are selling like hotcakes in the fish market in Portsmouth, Dominica.  The local divers have been killing this non-native and invasive species  and locals have taken up the cause by eating the delicious fish. I know that in some areas eating reef fish can put you at risk for contracting ciguatera. I also have heard that other areas are very low risk for ciguatera. Curiosity got the better of me and I fished around to find out some facts about ciguatera fish poisoning.

What is Ciguatera?

Ciguatera is a toxin that occurs in tiny marine organisms called dinoflagellates (Gambierdiscus toxicus). The dinoflagellates attach to marine algae, which is eaten by reef fish. Ciguatoxin is fat soluble and herbivorous fish consume this microalgae and the ciguatoxins are stored in the fat of fish and are bioaccumulated; the little fish eat the algae and get a dose of the ciguatoxin, then a larger fish eat many of the little fish and then a barracuda comes along and ingests the medium fish and the toxin is accumulated and passed through the food chain. Ciguatera is also accumulated in our fat; so you might not get sick the first time you consume the toxin. A sub symptomatic load might go unnoticed and only come to your attention when you get another dose of ciguatera that triggers the symptoms. You do not become immune to ciguatoxins.

What are the Symptoms of Ciguatera Poisoning?

The symptoms of ciguatera poisoning can vary from person to person. The most common symptoms include: nausea, vomiting, diarrhea, dizziness, headache, and numbness and tingling of limbs.  More acute symptoms include a feeling that your teeth are loose and confusing hot and cold temperatures. Death due to heart or respiratory failure occurs in rare cases. Symptoms may persist for months or years, or reoccur periodically. There is no antidote for ciguatera poisoning.  A trained doctor can make you more comfortable and reduce the symptoms.

Lionfish are now a common fish in Portsmouth, Dominica. Photo by Devi Sharp
Lionfish are now a common fish in Portsmouth, Dominica. Photo by Devi Sharp

What to know BEFORE Buying Fish about Ciguatera?

The symptoms are enough to scare anyone from eating fish, but not to worry, not all fish carry ciguatera.

There are two things to consider: where the fish was caught and where the fish feeds.

Fish that feed on reefs—or fish that feed on those fish—are high risk. For example barracuda feed at the top of the food chain so it is best to avoid them. Other high-risk fish include some species of grouper, snapper, parrotfish, eels, king mackerel, big eyed jack, amberjack and probably lionfish. The question of ‘where’ is harder to address, but some areas in the Eastern Caribbean are hotspots for ciguatera and others seem to be immune. In a comprehensive review of ciguatera in the Eastern Caribbean (Ciguatera in the Eastern Caribbean by David A. Olsen, David W. Nellis, and Richard S. Wood, National Marine Fisheries Review 1:13) the authors write that there are three primary centers of ciguatera concentration. The first is around Redonda between Antigua and Montserrat. The second area is between the eastern edge of the Saba Bank and along the southern edge of the Anguilla Bank. The third hot spot of ciguatera is along the narrow shelf south of Norman and Peter Islands in the British Virgin Islands. There are fewer cases of ciguatera reported south of Martinique.

Unfortunately, ciguatoxin is heat-stable, so cooking will not detoxify the fish. There are many folk methods to detect the toxin in a fish, but none have proven to be accurate. A test kit was developed in Hawaii, but is no longer available, so the best way to avoid ciguatera is to avoid eating reef fish and fish that are high order predators. Identify any fish you catch on your boat, even at sea and be very cautious of unknown fish in local markets.  Mahi, tuna and other pelagic fish should be free of ciguatera.

HAVE YOU SUFFERED FROM CIGUATERA POISONING?

If so, All At Sea would like to hear from you. Please send details naming type of fish eaten and where caught or bought, to: [email protected]

Editor’s note: Devi says she has eaten lionfish in Grenada and finds it delicious.

 

Devi Sharp is a retired wildlife biologist and exploring the Caribbean with her husband, Hunter on their sailboat Arctic Tern

 

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