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Fish, Crustaceans and Molluscs

Fish, crustaceans, and shellfish are listed as priority allergens in Canada. Collectively, these can be identified as ‘seafood’. This page focuses on facts specific to seafood allergy, available resources, and special considerations related to these allergens.

On this page:Statistics and facts on seafood allergy >
Seafood reference guide >
    Terms that may indicate the presence of seafood
    Foods that are likely and possible sources of seafood
    Possible sources of seafood in everyday products
    Substituting fish, crustaceans, and molluscs in your diet
Helpful resources >

Facts about fish, crustaceans and molluscs allergy

  • This food group is associated with a relatively high prevalence of food allergies.
  • Fish allergy affects 0.9% of children under 18 years of age and 0.5% of adults in Canada[1]. Crustaceans and shellfish allergy is estimated to affect 0.8% of children under 18 years of age and 1.6% of adults.
  • Crustacean and mollusc allergies predominantly affect adults and are less common among children.
  • Allergy to fish, crustaceans, and shellfish generally persists throughout life.
  • The term seafood refers to crustaceans and molluscs. Crustaceans have a rigid shell, while molluscs have a two-part shell. Lobster, shrimp, and crab are classified as crustaceans; while scallops, mussels and oysters as molluscs.
  • A person might be allergic to one or more species of fish, crustaceans and/or molluscs.
  • The risk of contamination between fish, crustaceans and molluscs is very high, especially in fish markets and grocery stores. If you are allergic to fish or seafood, it is better to avoid these points of sale and choose packaged products.
  • Imitation seafood (e. g. simulated crab) may contain fish and should be avoided.
  • Allergenic proteins from fish and seafood can be found in cooking fumes (e.g., steam from lobster cooking water, fish cooking in a pan). The simple inhalation of allergenic proteins can cause allergic reactions to people with highly sensitive allergies, even without consumption of the allergen [3].
  • Allergy or food poisoning? Signs and symptoms of an allergic reaction to fish are sometimes confused with scombroidosis, a food poisoning to histamine. The symptoms of scombroidosis (burning sensation in the throat, facial swelling, itching, rashes, and abdominal pain) are similar to those of anaphylaxis [4]. Scombroidosis cases are most often associated with the consumption of tuna, bonito, and mackerel due to the high amount of histamine found in their flesh when not fresh. It is the decomposition of the fish that allows for the formation of histamine. However, this decomposition is difficult to detect, because it often occurs before a foul-smelling odour is released from the fish.

Fish, crustaceans and molluscs – REFERENCE GUIDE

Fish, crustaceans and molluscs REFERENCE GUIDE, PDF format (0,5 Mo) (in French)
Terms that may indicate the presence of :
Fish (non-exhaustive list)
AnchoviesAnchovy pasteAnglerfish
BassYellow tunaBonito
CatfishCaviarChannel catfish
Fish broth and sauceGoldenGrondin
Nuoc MamOrange roughyPerch
PompanoRed mulletRedfish
Sea breamSea toadShad
Tarama (mullet-based recipe)TassergalTilapia
WhitingYellow PerchYellowtail flounder
Crustaceans (non-exhaustive list)
Shrimps and prawnsSpiny lobsterTomalli
Molluscs (non-exhaustive list)
Oyster saucePeriwinkleScallop
Sea urchinSnailSolen
SquidSt James Shell 
Health Canada’s food allergen labelling regulations established in 2012 prohibit use of the following terms. Manufacturers must declare the presence of fish, crustaceans and shellfish in the list of ingredients either on the label of their product or in the words “Contains”. However, it is important to keep those terms in mind when travelling, as regulations vary from one country to another. In some cases, it may also be useful to know them when we are offered artisanal or homemade products.
Foods that are likely sources of fish, crustaceans, and molluscs (non-exhaustive list)
Court-bouillonFisherman’s plateChitosaneBouillabaisse
Cocktail made from Clamato tomatoes (clams)
Foods that are possible sources of fish, crustaceans, and molluscs (non-exhaustive list)
SoupsKamaboko (crustaceans)Vin (fish)Chowder
Entrance and appetizersPot au feuYogurt with omega-3 (fish)Juice with omega-3 (fish)
Cocktail with spicy tomato base
Possible sources of fish and shellfish in commonly used products (non-exhaustive list)


  • Omega-3 supplements (for more information, see our article in
    French on dietary supplements)
  • Gardening products


  • Omega-3 supplements (for more information, see our article in
    French on dietary supplements)
  • Gardening products
Note: To find out if common products contain allergens, it is important to read the labels and contact the manufacturer. Food allergen labelling regulations apply only to packaged foods; they do not apply to non-food products.

Resources for people with fish, crustaceans and molluscs allergy

[1] Soller, S et coll. (2015). Adjusting for nonresponse bias corrects overestimates of food allergy prevalence. Journal of Allergy and Clinical Immunology, 3(2), 291-293. DOI 10.1016/j.jaip.2014.11.006
[2] Office québécois de la langue française (2014). Fiche terminologique : fruits de mer. Repéré à
[3] Dufresne, C. (2009). Vivre avec les allergies alimentaires : un guide complet pour comprendre et prévenir les réactions allergiques. Montréal, Québec : Les éditions La Presse, 253 p.
[4] Agence canadienne d’inspection des aliments (2012). Faits sur la salubrité des aliments : Intoxication par des scombroïdes (scombroïdose). Repéré à…