The Shenzhen Municipal Public Health Bureau issued a food safety alert after 67 people became ill after eating deep-sea fish, the Shenzhen Special Zone Daily reported Thursday.

The bureau warned restaurants should not serve deep-sea fish that may contain ciguatoxin.

The first poisonings occurred in April in Nanshan District when six people became ill after eating Leopard Coral Grouper.

The most serious poisonings struck down 49 people after they had eaten Humphead Wrasse in two branches of a chain restaurant.

Another Humphead Wrasse poisoned seven in a Futian restaurant.

A family of five was also poisoned from eating Humphead Wrasse after buying it at a Dongmen market.

All recovered after hospital treatment.

Ciguatoxin originates from a toxic marine microorganism that lives on dead coral reefs and algae. The toxin passes up the food chain through herbivorous fish, carnivorous fish, and finally to humans.

Experts said that the larger the fish, the higher the concentration of toxin, which can not be destroyed by cooking.

Victims experience severe gastrointestinal and neurological symptoms a few hours after eating the fish. Excessive consumption could lead to death. Leopard Coral Grouper, Humphead Wrasse and Black Saddled Coral Grouper -- all deep sea fish -- have been linked to ciguatoxin poisoning.

Diners were warned to be prudent when eating deep-sea fish and were advised not to eat those weighing more than 1.5 kilograms.

(Shenzhen Daily December 3, 2004)