Freezing fish and fishery products

Information about freezing fish and fishery products

Fish laying on ice

Why freezing is required

Fish parasites such as Anisakis larvae (parasitic worms) are a problem in certain species of wild fish including:

  • salmon
  • herring
  • cod
  • other fish species including monkfish

All fish and fishery products must be checked and any with visible parasites removed before the fishery product is sold. As well as being unsightly, if eaten alive, Anisakis larvae can cause human illness or allergic reactions in some people. Illness can include abdominal pain and nausea.

Cooking will kill the parasites. Freezing provides an alternative process for killing any parasites:

  • that may be undetected in fish and fishery products
  • that are not cooked prior to consumption

Our research shows that there is a low risk of parasites from farmed salmon.

The European Food Safety Authority (EFSA) reviewed the evidence on the presence of parasites in wild and farmed fish in its Opinion of 2010. This Opinion sets out specific time and temperature treatments required to kill the parasites. 

Fish freezing requirements

Freezing requirements apply to all food businesses that place fish and fishery products on the market such as restaurants, fish suppliers and fish buyers. This is to protect consumers from any harmful effects that might be caused by parasites that are naturally present in the fish.

Under food hygiene legislation, certain fishery products intended to be eaten raw need to be frozen before use. These include:

  • sushi
  • sashimi
  • cold smoked fish where the smoking process does not achieve a core temperature of 60°C for at least one minute

Any treated products where the processing treatment doesn’t kill the parasites must also be frozen before consumption. These can include:

  • gravlax
  • carpaccio
  • some pickled herring products
  • some marinated fish products
  • salted fishery products

For parasites other than trematodes the freezing treatment must consist of lowering the temperature in all parts of the product to at least either:

  • –20°C for not less than 24 hours
  • –35°C for not less than 15 hours

Some exemptions to the freezing requirements apply to fish reared under certain conditions with minimal risk of parasite infection. 

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