Health department issues warning on toxin commonly found in tropical waters

PUBLISHED : Thursday, 02 August, 2001, 12:00am
UPDATED : Thursday, 02 August, 2001, 12:00am

The Health Department yesterday warned against eating large coral reef fish after 20 people reportedly fell ill with food poisoning.

The department said all those affected had eaten leopard coral grouper, hump head wrasse and moray eel - which are suspected of carrying ciguatoxin, a poison found in coral reef fish - in the last four days.

The department said people should avoid eating large coral reef fish, especially those weighing more than 1.8kg.

If they must eat the fish, they should do so in small quantities and infrequently. The toxin is usually concentrated in the fish's head and skin, the department said.

'The toxin cannot be destroyed by cooking,' a department spokesman said.

He said that large fish were more toxic than smaller ones as the toxins built up over time.

Ciguatera symptoms include numbness of the mouth and the limbs, vomiting, diarrhoea, hot and cold flushes, and joint and muscle pains.

People with the symptoms are advised to seek medical help immediately.

Other fish commonly associated with ciguatera poisoning in Hong Kong are black fin red snapper, blue spot snapper, mangrove snapper and tiger grouper.

All 20 victims, who had shown the symptoms, have recovered.

In two cases, the victims ate out at restaurants. In one case, a hump head wrasse was bought from a wet market and another person was reportedly poisoned after eating in a mainland restaurant.

Ciguatera fish poisoning is common in tropical waters where large coral reef fish feed on small fish that eat toxic algae.

However, people cannot tell just by looking if a fish is toxic or not, the department's spokesman said.

Meanwhile, thousands of fishermen set sail from Hong Kong yesterday following the end of a two-month fishing moratorium in the South China Sea.

But Leung Wai-ying, chairman of the Hong Kong Fishermen Association, said catches were no better than before the moratorium because local fishermen were facing increasing competition from their Guangdong counterparts.

'Over the past years, the number of fishing boats have increased significantly and local fishermen have to compete with them for limited fishing reserves,' he said.

Mr Leung said each fishing household in general lost between $50,000 and $70,000 during the moratorium period and he hoped the Agriculture, Fisheries and Conservation Department would offer extra financial assistance to them.

The department has handed out $8 million in loans to 257 fishing families in the past two months.