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Chemical structure of the ciguatoxin CTX1B

Ciguatoxins are a class of poisonous organic compounds found in some fish that cause ciguatera.

There are several different chemicals in this class. "CTX" is often used as an abbreviation in their names.

Toxic effect[edit]

Some ciguatoxins lower the threshold for opening voltage-gated sodium channels in synapses of the nervous system. Opening a sodium channel causes depolarization, which could sequentially cause paralysis, heart contraction, and changing the senses of heat and cold. The condition is known as ciguatera. Others affect calcium channels.

Ciguatoxins are lipid-soluble, able to cross the blood brain barrier, causing both central and peripheral neurologic symptoms.

The major symptoms will develop within 1-3 hours of toxin ingestion: vomiting, diarrhea, numbness of extremities, mouth and lips, reversal of hot and cold sensation, muscle and joint aches. The symptoms may last from days to weeks or even months depending on each individual situation. There is no antidote for ciguatoxin poisoning.

Bioaccumulation route[edit]

Ciguatoxin is produced by Gambierdiscus toxicus, a type of dinoflagellate, that are eaten by big coral reef fish, such as grouper, wrasse, triggerfish, lionfish, and amberjack. Ciguatoxin usually accumulates in skin, head, viscera, and roe of the fish.

Ciguatoxin cannot be destroyed by cooking.[1] Rapid testing for this toxin in fish marketed as food is not standard.


  1. ^ Swift A, Swift T (1993). "Ciguatera". J. Toxicol. Clin. Toxicol. 31 (1): 1–29. doi:10.3109/15563659309000371. PMID 8433404. 

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