The Auckland District Health Board has issued a public health warning against eating tropical marine fish imported from the Pacific Islands.

The warning was issued after a recent case of ciguatera poisoning in which four family members experienced numbness, difficulty walking, itchy skin and painful joints after eating fish privately imported from Fiji.

There is no treatment and in the worst cases the poisoning, which is caused by the ciguatoxin in tropical fish, can cause vomiting, diarrhoea, cramps, reversal of hot and cold senses, high blood pressure, paralysis, and even coma and death. These symptoms, which usually clear up in a few days, although possibly within weeks or months, are used to diagnose the poisoning, which cannot be detected through any laboratory tests.

Rare, imported tropical fish are offered as specialities in some restaurants, but the Health Board warned that cooking or freezing the meat does not destroy the toxin. It also said that internal organs should not be eaten.