The Centre for Health Protection is investigating a food poisoning case involving seven people, suspected to be caused by fish containing ciguatoxin.

The two males and five females, aged six to 50, developed limb numbness, diarrhoea and abdominal pain six to 14 hours after eating a large grouper in a Western District restaurant on June 5.

Their symptoms were generally mild and none required hospitalisation.

To prevent ciguatera fish poisoning:

* eat less coral reef fish;

* eat a small amount of coral reef fish at any one meal and avoid having a whole fish feast in which all the dishes come from the same big fish;

* avoid eating fish head, skin, viscera and roe, which usually have higher concentrations of toxin; and,

* when eating coral reef fish, avoid consuming alcohol, peanuts or beans as they can aggravate the poisoning.

Seek medical treatment immediately if symptoms appear.