Illness from eating varieties of poisonous fishes.
Most cases are caused by one of three toxins : ciguatera poisoning, from fishes in whose flesh dinoflagellates have produced toxins; tetraodon poisoning, from a nerve toxin in certain pufferlike fish (fugu); and scombroid poisoning from spoilage bacteria in fish of the mackerel family. Shellfish poisoning from eating certain mussels, clams, and oysters has in some instances been traced to the plankton they sometimes feed on.