Experts estimate that up to 50,000 people worldwide suffer ciguatera poisoning each year, a rarely fatal but growing menace from eating exotic fish, with more than 90 percent of cases unreported.
And scientists say the risks are getting worse, because of damage that pollution and global warming are inflicting on the coral reefs where many fish species feed.
Dozens of popular fish types, including grouper and barracuda, live near reefs. They accumulate the toxic chemical in their bodies from eating smaller fish that graze on the poisonous algae. When oceans are warmed by the greenhouse effect and fouled by toxic runoff, coral reefs are damaged and poison algae thrives, scientists say.