In ciguatera seafood poisoning, which of the following is NOT a common source of the toxin?

• A. Barracuda
• B. Snapper
• C. Tuna
• D. Grouper

Answer: (C)

Ciguatera toxin arises from dinoflagellates in warm tropical waters and concentrates up the food chain, so the fish most likely to harbor high toxin levels are large reef-dwelling predators. Barracuda, grouper, and snapper are classic examples because they live on coral reefs and sit near the top of that reef food web, allowing the toxin to accumulate in their flesh. Tuna, while a large predator, mostly inhabits the open ocean and preys on different species, so it does not accumulate ciguatoxins to the same extent. Therefore, tuna is not a common source of the toxin in ciguatera poisoning.