Ciguatera Fish Poisoning

Coral reef fish

Ciguatera fish poisoning is reported in Hong Kong from time to time, so what is ciguatoxin? What are the principal symptoms of ciguatoxin poisoning? How to prevent ciguatoxin poisoning?

Ciguatoxin originates from a toxic marine microorganism, dinoflagellate, which lives on dead coral reef and algae. In fact, coral reef fish is not toxic, but fish eating the algae accumulates the ciguatoxins, and the effect is magnified through the food chain so that larger predatory fish is more toxic. Ciguatoxin usually accumulates in the head, skin, viscera and roe of the fish. Ciguatoxin does not cause any harm to the coral reef fish. Hence, ciguatoxic fish cannot be identified by its appearance, odour or texture. As the toxin is highly stable, it cannot be destroyed by cooking, refrigeration, drying and digestion.

People affected may show symptoms of mouth and limbs numbness, vomiting, diarrhoea, nausea, abdominal pain and pain of the joints and muscles. If excessive toxin was consumed, the circulatory and nervous systems would be affected.

According to past records of ciguatera fish poisoning cases reported in Hong Kong, fish species which are more likely to contain ciguatoxins include Moray Eel, Potato Grouper, Speckled Blue Grouper, Tiger Grouper, High Fin Grouper, Hump Head Wrasse, Areolated Coral Grouper, Black Saddled Coral Grouper, Lyretail, Black Fin Red Snapper, Flowery Grouper and Leopard Coral Grouper.

To prevent ciguatera fish poisoning, members of the public should observe the following measures: