Fish and shellfish poisoning

There are three main types of poisonous fish.

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Ciguatera poisoning

Ciguatera poisoning occurs when eating any of >400 species of fish found near tropical reefs in Florida, the West Indies, or the Pacific Ocean, where dinoflagellates produce the toxin, which accumulates in the flesh of the fish. Older and larger fish (grouper, snapper, kingfish) contain more poison. The odor of the fish is unchanged, and no known method of handling (including cooking) prevents poisoning. Signs of poisoning appear within 2-8 hours. Intestinal colic, nausea, vomiting, and diarrhea last for 6-17 hours, then may develop paresthesia, headache, myalgia, pruritus, facial pain, and abnormal thermal sensations. Abnormal sensory sensations and nervousness may result in incapacitation for months. There have been attempts to treat such poisonings with intravenous administration of mannitol, but no noticeable effect has been achieved.

Mackerel poisoning

Scombridae poisoning is caused by high histamine levels in the fish meat due to the decomposition of bacteria after it is caught. The most common representatives are tuna, mackerel, mahi-mahi or mudskippers. The taste of the fish can be bitter or unpleasant (acrid). Twitching of the facial muscles, nausea, vomiting, pain in the epigastrium, skin rashes occur a few minutes after eating and disappear within 24 hours. Symptoms are often mistaken for an allergy to seafood. Unlike other fish poisonings, this can be prevented by storing the fish correctly after catching it. Treatment includes the introduction of H1- and H2-receptor blockers.

Tetrodotoxin poisoning (fugu fish)

Tetrodotoxin poisoning most commonly occurs from eating puffer fish, >100 species of which (marine and freshwater) contain tetrodotoxin. Symptoms are similar to those of ciguatera poisoning, and potentially fatal paralysis of the respiratory muscles may occur. Tetrodotoxin is not destroyed by cooking or freezing.

Shellfish poisoning

Typical from June to October, especially on the Pacific and New England coasts, when mussels, oysters, scallops and other shellfish become infected with poisonous dinoflagellates that form red tide. Dinoflagellates secrete the neurotoxic poison saxitoxin, which is resistant to cooking. Paresthesias of the face around the lips and nose occur 5-30 minutes after eating. Then nausea, vomiting, intestinal colic, and muscle weakness appear. Without treatment, paralysis of the respiratory muscles can lead to death; survivors have no consequences.