The UK Food Standards Agency is reminding caterers and consumers of the importance of refrigerating fish properly, following a number of incidents involving scombrotoxic fish poisoning during the (UK) summer.

Scombrotoxic fish poisoning is linked to eating fish from the family that includes tuna, mackerel, and herring. It is caused when fish and fish products are not refrigerated correctly. Warmer temperatures allow bacteria to multiply and produce a chemical called histamine at levels that can make people ill if it's eaten. Cooking the fish will not destroy histamine.

Four incidents of scombrotoxic fish poisoning have been reported to the Health Protection Agency between the end of June and the end of July, which resulted in 10 people becoming ill. All of the outbreaks involved catering establishments and are thought to have resulted from poor food handling or inadequate refrigeration.

Symptoms are similar to those of an allergic reaction; they include skin rash, low blood pressure, vomiting and diarrhoea. Symptoms also include headaches, dizziness, palpitations, and abdominal cramps. Symptoms can occur as quickly as 10 minutes after eating the affected fish and may be serious enough to require urgent medical attention, although they usually resolve within 24 hours.

Storing fish safely

The Agency advises caterers and consumers to:

* put fish in the fridge or freezer (in covered containers) as soon as possible - ensure that fridges or chilled display equipment are set at a temperature of 5?C or below, and freezers are set to a minimum of -18°C

* thaw fish in the fridge overnight, or to thaw it more quickly, use a microwave. Use the ‘defrost' setting and stop when the fish is icy but flexible

* wash hands thoroughly before and after handling fish

* buy fish from a reliable source

As well as following this advice for fresh fish, it also applies to fish products (e.g. canned tuna after it's been opened).