Medical / Travel

Fish Poisoning: Ciguatera


Ciguatera occurs in over 400 species of reef dwelling fish in tropical and sub-tropical countries. Ciguatera poisoning can have short and long term effects mimicking several other conditions. You need to know the symptoms and treatment.

Poisoned reef dwelling predators include barracuda, hog fish, king mackerel, snapper, and grouper to name just a few. It all begins with carrier algae and primarily the toxins Ciguatoxin and Maitotoxin. Smaller fish eat the poisonous algae, bigger fish eat the smaller fish, and right on up the food chain. Ciguatera is most often found at the top of the food chain in larger fish who have had years to accumulate the poison. It is found in their skin and especially concentrated in the liver and internal organs.

Statistics as to the number of people with ciguatera poison are hard to come by because there are so many unreported cases. Suffice it to say that if you eat a poisoned fish, you have a 75-100% chance of getting ciguatera poisoning.

You will never know if a fish is infected by looking, smelling, or tasting it. No amount of boiling, frying, or heat will kill this toxin. There is no lab work available that is 100% reliable to test for Ciguatera prior to consumption. There are time consuming tests like the mouse bioassay and radio immune assays that are not practical for pre-consumption. evaluation.


  • Nausea, vomiting, abdominal pain, diarrhea. Often the first symptoms. Onset can be in 15 minutes to 24 hours. The average onset after consumption is 6-12 hours. Once symptoms are noticed they gradually increase over the next 6-12 hours.
  • Temperature sensation reversal. Hot things feel cold; cold things feel hot. This occurs with this type of poisoning and very few other things. If you have eaten a predator fish and have this symptom, you almost certainly have ciguatera poisoning.
  • Numbness around the mouth, dental pain, metallic taste in the mouth.
  • Painful sensations possibly involving the entire body.
  • Pain in the joints and/or muscles.
  • Weakness
  • Dizziness, vertigo, poor coordination (ataxia).
  • Itching
  • Respiratory paralysis. Probably the most serious symptom. Seek medical attention at the first sign of shortness of breath.
  • Heart signs. Slowing of heart rate, low blood pressure (if possible log blood pressure and heart rate every 30 mins. This will document progression and let medical personnel determine the seriousness of the problem.)
  • Sweating and chills.
  • Ciguatera is sexually transmitted, is present in breast milk and crosses the placenta. It is thought to be a cause of pre-mature birth and spontaneous abortion.

Note: You can see, the symptoms can be almost anything. Use common sense. If you have eaten a predator fish within the last 15 mins.-24 hours and have any of the above symptoms or similar, especially if they are getting progressively worse, seek medical attention.


Like so many things, there is no medicine that counteracts the poison. Symptoms are treated as they arise.

  • Mannitol ( a diuretic) infusions are the mainstay.
  • Activated charcoal by mouth.
  • Atropine to increase heart rate, Dopamine.
  • Tricyclic anti-depressants.
  • Prednisone/Decadron
  • Many other medications depending on symptoms.
  • The length of symptoms vary but can be present for months.

Note: There is very little that can be done in the field, medication wise, due to the often complex symptoms. The field objective is to 1) Recognize the symptoms as they relate to fish ingestion. 2) Monitor breathing, heart rate, respiratory rate, and blood pressure. 3) Calmly reassure the victim. 4) Seek medical attention for treatment and documentation of poisoning.

Note: Although a person has had ciguatera in the past, they will have symptoms again if a poison fish is eaten later on i.e. no one develops immunity or resistance.

Warning: There are all kinds of folk lore and tales about ciguatera. Some say, if flies avoid the fish you should also, if ants crawl on it it is okay to eat, and if cats like it you will too. Don’t believe any of this. It is believed that domestic pets can be poisoned as well as humans.

See: My World-Case Studies for more on ciguatera.



One thought on “Fish Poisoning: Ciguatera

  1. Pingback: My World-Ciguatera | International Travel Advisor

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