Kokoda ciguatera risk check

Ciguatera fish poisoning is the one endemic food-safety risk on the Fijian reef. It's caused by ciguatoxin, a heat-stable neurotoxin produced by the dinoflagellate Gambierdiscus toxicus, which lives on dead coral and macroalgae. Small herbivores eat the algae; predators (grouper, barracuda, moray eel, large snappers, sharks) accumulate the toxin up the food chain — a process called biomagnification. The older and larger the predator, the more toxin it usually carries.

Because the toxin is heat-stable and odourless, you cannot smell it, taste it, or cook it out. Freezing doesn't help either. The single best mitigation is choosing a small, herbivorous or short-food-chain fish — lagoon mullet (kehu), small reef fish under 3 kg, or pelagic tuna — and avoiding large predator fillets.

Symptoms typically appear 1–6 hours after eating and include nausea, vomiting, diarrhoea, muscle aches, and the characteristic reverse hot-cold sensation: cold drinks feel burning-hot, cold water on the hands feels electric. Severe cases involve bradycardia and hypotension and warrant an IV drip. There is no antidote, but the toxin is usually cleared in days to weeks with supportive care.

Risk is also seasonal: warmer water (March–September in Fiji) and post-cyclone reef disturbance (sediment run-off, dead coral) increase algal blooms. Outer-reef drop-offs and open reef are higher risk than turbid lagoon waters. Buying from a busy market in Suva or Lautoka, where turnover is high and the vendor knows the species, is the safer path than a roadside fillet whose origin you can't trace.

• Not medical. This is a heuristic risk check, not a diagnosis. If you feel tingling lips, metallic taste, or temperature reversal after a reef-fish meal, see a doctor or go to the nearest hospital (Suva CWM, Lautoka, Nadi).
• Toxin load is not visible. Two fish of the same species caught on the same day can differ by an order of magnitude in ciguatoxin. There is no field test kit — the only definitive method is mouse bioassay or LC-MS in a reference lab.
• Risk score is approximate. Real risk depends on the specific reef, the recent cyclone history, and the individual fish's age and fat content. Use this as a trip-planning prompt, not a guarantee.
• Personal history matters. Previous ciguatera poisoning makes you more sensitive to future episodes. Pregnant travellers and people with cardiovascular history should treat all large predator fillets as off-limits.
• Allergies vs ciguatera. Scombroid (histamine) poisoning from poorly chilled tuna is a different condition, with rapid flushing and rash. Ciguatera is neurological and delayed.