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Toxins in seafood


Last updated: 23 December 2020

What are they?

  • Toxins (poisons) can be present in some shellfish and fish
  • These toxins are known as:
    • amnesic shellfish toxin
    • diarrhoetic shellfish toxin
    • neurotoxic shellfish toxin
    • paralytic shellfish toxin
    • ciguatoxin and
    • histamine
  • The toxins come from algae that shellfish and fish feed on, or from bacteria naturally present in some fish
  • Foods at higher risk of contamination are:
    • clams, oysters, mussels, scallops and crabs (for shellfish toxins)
    • coral fish including Chinaman fish, red bass, some wrasse, tropical snappers and coral trout (for ciguatoxins)
    • Scombridae and Scomberesocidae fish including mackerel, tuna, sardines, anchovy and marlin (for histamine).

What’s the risk?

  • These toxins can cause gastro or neurological illnesses called:
    • amnesic, diarrhoetic, neurotoxic or paralytic shellfish poisoning
    • ciguatera poisoning
    • Scombroid or histamine poisoning
  • Severe illness can result in coma, respiratory failure, paralysis or death
  • Anyone can get ill from toxins but children are more likely to be seriously ill or die, especially from paralytic shellfish poisoning
  • Toxins are not destroyed by freezing or cooking.

Reduce your risk

  • Buy seafood from a trusted supplier that is a registered food business
  • Keep seafood cold (5°C or colder)
    • refrigerate it immediately after buying it
    • if its frozen, thaw it in the fridge before cooking
    • if you catch your own fish, chill it on ice immediately
  • Avoid eating large fish from warm ocean waters, especially the head, roe or organs
  • If you are harvesting shellfish or reef fish, check with local authorities which species and waters are safe for harvesting.

Symptoms of toxin poisoning

  • Generally these toxins cause symptoms within minutes or hours of eating contaminated seafood. Amnesic shellfish poisoning symptoms usually take 1-2 days to appear.
  • Symptoms depend on the toxin. They can be gastro symptoms such as nausea, diarrhoea, abdominal cramps and vomiting. If the toxin affects the nervous system, symptoms can include numbness, tingling, confusion, paralysis, fainting and respiratory problems. Severe cases can be fatal, particularly from amnesic and paralytic shellfish poisoning.
  • Symptoms can last a few days up to several months.


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