Press Release

Public advised to be cautious of ciguatera fish poisoning

August 1, 2001

The Department of Health today (August 1) advised the public to be extra cautious of eating large coral reef fish, particularly those weighing over three catties, as they may contain ciguatoxin which may cause food poisoning.

The advice followed four food poisoning cases, affecting a total of 20 people, suspected to be caused by fish containing ciguatoxin in the last four days. The cases developed symptoms of ciguatoxin poisoning after eating coral reef fish including leopard coral grouper, hump head wrasse and moray eel. All of them recovered after treatment.

A spokesman for the Department said ciguatera fish poisoning is not uncommon in tropical areas. It is mainly associated with the consumption of big coral reef fish which has accumulated the toxin in its body, in particular head, viscera and skin, through eating small fish that consume toxic algae in coral reef seas.

The larger fish is therefore more likely to carry higher amounts of the toxin and it cannot be told from the appearance of the fish if it contains any toxin. Though less common, the chance of toxin accumulating in smaller fish cannot be ruled out.

People affected may show symptoms of numbness of the mouth and the limbs, vomiting, diarrhoea, reversal of sensation of coldness and hotness, pains of the joints and muscles.

He said that most persons affected by ciguatoxin will recover without long term health sequelae. However, if excessive toxin is eaten, the circulatory and nervous systems will be affected.

"The toxin cannot be destroyed by cooking", the spokesman said.

To prevent ciguatera fish poisoning, the spokesman advised that the following should be observed:-

• Avoid consuming large coral reef fish, especially those larger than three catties;
• Avoid eating the head, skin and viscera especially liver and gonads of big coral reef fish where the toxin is most concentrated;
• Reduce the frequency of eating big coral reef fish;
• Eat only a small quantity of coral reef fish at any one meal; and
• Seek medical care when symptoms appear.

He said that other fish commonly found associated with ciguatera fish poisoning in Hong Kong are black fin red snapper, blue spot snapper, mangrove snapper, tiger grouper and other coral reef fish species.