Tip of the Week

Did you know that leaving fish to defrost in water in a sink or out in the kitchen can cause an allergic reaction even when fully cooked?

A common form of food poisoning attributed to fish is Scombroid food poisoning. The symptoms of this type of food poisoning are similar to having an allergic reaction.

Fresh fish needs to be frozen at source or kept at very low temperatures as the flesh starts to spoil at the relatively low temperature of 16°C.

Histamine is a naturally occurring amino acid that is present in fish.  At temperatures above 16°C, histamine is converted into biogenic amine histamine which results in Scombroid food poisoning.

If you defrost fish in the kitchen or in water in the sink it is likely the outside flesh will reach 16°C and so a build-up of histamine occurs.  Histamine can occur in fresh fish from temperatures as low as 7°C; however it is more likely to occur at temperatures of 16°C or above.  This Histamine is not destroyed by normal cooking temperatures, so even properly cooked fish can still result in poisoning.

Histamine is also the natural chemical responsible for true allergic reactions and, as the symptoms produced by scombroid food poisoning are similar, it often gets misidentified as a food allergy.


Always defrost fish in the refrigerator under controlled temperature conditions.  The outside temperature of the fish will easily rise to 16°C  if defrosted in a sink of water or a warm kitchen.

Weekly Food Fact

Did you know that there are more species of fish than all the species of amphibians, reptiles, birds and mammals combined.

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