Ciguatera fish poisoning

Ciguatera toxins are produced by small algae-like organism (dinoflagellate), which attaches itself to algae growing in warm ocean reef areas. Small plant-eating fish eat the toxic algae and in turn are eaten by larger predatory fish. Ciguatera fish poisoning occurs when people eat fish that have accumulated a significant amount of the toxin.

Any predatory fish that feeds on warm ocean waters can be carriers of ciguatera toxins.

Ciguatera toxin does not affect the appearance, odour or taste of the fish so you will not be aware that the toxin is present. Freezing or cooking the fish once it has been contaminated will not kill the toxin or prevent illness.

Symptoms usually start between 1 to 48 hours after eating a toxic fish. The time before illness starts and the range of symptoms can depend on:

• how much fish is eaten
• how much toxin is in the fish
• each person's susceptibility to the toxin.

You will generally experience runny poos, throwing up and stomach cramps (gastrointestinal symptoms) first. These often start in the first 24 hours and last for a few days.

Neurological symptoms may happen at the same time as the gastrointestinal symptoms or follow 1 to 2 days later. In some cases, neurological symptoms may happen without gastrointestinal symptoms. Neurological symptoms can include:

• tingling and numbness in fingers, toes, around lips, tongue, mouth and throat
• reversed temperature sensation
• burning sensation or pain on contact with cold water
• dizziness or light headedness
• joint and muscle pains with muscular weakness
• headache
• feeling more tired than usual (fatigue and lethargy)
• itch.

In some severe cases you may have difficulty breathing.

Most people recover completely within a few weeks. But you may have episodes of neurological symptoms over months to years.

Your healthcare provider will diagnose ciguatera fish poisoning by:

• checking if you have eaten fish commonly associated with ciguatera fish poisoning
• gastrointestinal and neurologic symptoms consistent with ciguatera fish poisoning, especially if cold is perceived as hot or uncomfortable (temperature-related dysesthesia)
• ruling out other potential causes
• confirmation of ciguatoxin in the consumed fish if possible.

Treatment is aimed at relieving gastrointestinal symptoms.

Rest and drink plenty of fluids to prevent dehydration. See the self care section on our gastroenteritis page for more details.

Diarrhoea and vomiting (gastroenteritis) (internal link)

Some medicines may be used depending on the other symptoms you experience.

To help avoid your symptoms coming back, for 6 months after having ciguatera fish poisoning, we recommend you:

• do not consume alcohol, caffeine, fish, fish sauces and nuts
• avoid excessive or strenuous physical activity.

Men are advised to use a condom during sexual activity for the next 6 months to reduce the risk of painful sex for their partners.

Once completely recovered, initially eat only a small portion of warm water ocean fish, no more than 200 grams. If symptoms start again, seek medical advice and avoid eating warm water ocean fish for a few more months.

• Avoid eating the head, roe, liver or other organs of warm water ocean fish. As the toxin is highest in these parts of the fish.
• Vary the type of warm water fish eaten.
• Avoid eating large warm water fish. Limit whole weight to around five kilograms per fish, as ciguatera fish poisoning occurs more frequently when larger fish are eaten.
• When first eating a warm water ocean fish, eat a small portion only — no more than 150 to 200 grams. If ciguatera-like symptoms develop, do not eat further portions of that fish.