Ciguatera food poisoning is caused by eating fish that have accumulated a high level of natural toxins from certain micro-algae in coral. Ocean fish is not contaminated because it doesn't feed on coral. It is reef fish and other fishes eating them that are infected. Although deaths from ciguatera poisoning are rare, the most serious cases can lead to fatal respiratory paralysis.
Prevalent in the Pacific islands, ciguatera has existed for thousands of years; but it is more of a concern these days because the toxic algae grow on dead coral, and the death of coral is increasing due to climate change.
Around 15,000 Americans get the disease every year. Common reef fish that can be contaminated by ciguatera include barracuda, moray eel, snapper, grouper, sturgeon, and sea bass.