Fish safety: ciguatera poisoning and reef species risk

Ciguatera is a neurotoxin produced by reef microalgae that bioaccumulates in fish and can cause lasting neurological symptoms; it cannot be detected by taste or removed by cooking, and researchers are working on screening methods and forecasting models.

A diver's account from the Florida Keys describes spearfishing and eating lionfish and raises questions about which reef fish are safe to eat. Ciguatera fish poisoning is caused by microalgae that grow near coral reefs and produces a neurotoxin that moves up the food web. The toxin is not detectable by taste or smell and is not removed by cooking or freezing. Scientists report expanding geographic risk as ocean temperatures rise and tropical species move into higher latitudes. Key facts: - Ciguatera is the most common nonbacterial seafood poisoning and is reported to affect up to 500,000 people per year worldwide. - The toxin originates from reef microalgae and bioaccumulates, so concentrations tend to be higher in larger, predatory reef fish. - More than 400 species of reef fish can carry ciguatera; species often cited as higher risk include large predatory fish over about 10 pounds such as barracuda, red snapper, grouper, amberjack and sea bass. - The toxin cannot be seen, tasted, or smelled, and cooking, cleaning, or freezing does not eliminate it; there is currently no known antidote. - Tests of lionfish from 74 Caribbean locations found that fewer than one percent had high levels of ciguatera, and researchers are developing rapid screening tools, treatments and forecasting models. Summary: Ciguatera poses a continuing public-health and food-safety concern because the toxin accumulates in reef food webs, is undetectable by normal sensory checks, and has no known cure. Researchers are working on screening methods, treatments and models to forecast risk, but reliable prediction and a cure are not established at this time.