Fish allergy: where fish arrives without the word fish

Fish allergy and shellfish allergy are separate conditions involving different proteins, and having one implies nothing about the other. The difficulty with fish is how often it does the work of a seasoning rather than an ingredient.

A separate allergy from shellfish

Fish allergy is most often a reaction to parvalbumin, a protein found across finned fish. Shellfish allergy usually involves tropomyosin, an unrelated protein found in crustaceans and molluscs. They are different allergies, and the common assumption that seafood is one category is wrong in both directions: many people with a fish allergy eat prawns without difficulty, and many with a shellfish allergy eat salmon.

Fish allergy is also more often lifelong than the childhood allergies to milk and egg, and reactions can be provoked by cooking vapour in a way that is unusual among food allergies.

Dashi is the one to know about

Dashi is the stock underlying most Japanese cooking, and it is made from katsuobushi, dried and fermented bonito, a fish. It is in miso soup, in ramen broth, in the dipping sauces for noodles, in many simmered dishes and in a great many seasoning blends and instant powders. A dish can read as entirely vegetable and be built on it.

The same applies more widely across Asian cooking. Fish sauce, nam pla and nuoc mam are anchovy-based and underpin Thai and Vietnamese food. Many oyster sauces and XO sauces contain dried fish alongside the shellfish.

The Western hiding places

Worcestershire sauce is made with anchovies, which catches people because it is used as a general savoury seasoning in dishes with no fish in them, including many gravies, marinades and a Bloody Mary. Caesar dressing is anchovy-based for the same reason. Patum peperium, or gentleman's relish, is anchovy.

Surimi deserves a note of its own. Crab sticks, seafood sticks and much of the imitation crab in supermarket sandwiches and sushi are surimi, which is made from white fish, usually Alaska pollock. So a crab stick is a fish product, and it is a genuine risk for someone with a fish allergy and frequently not a risk for the shellfish allergy the name suggests, although flavourings derived from shellfish are sometimes added.

Isinglass, made from fish swim bladders, is used to fine some beers and wines. Very little remains in the finished drink and it does not have to be declared, but it exists.

Names worth knowing

Ingredients worth recognising on sight, with the other names each one appears under. Several of these are seasonings rather than anything that reads as fish.

Bonito

KatsuobushiBonito FlakesBonito ExtractDashi

Anchovy

Anchovy PasteAnchovy Extract

Fish Sauce

Nam PlaNuoc MamPatis

Surimi

Crab StickFish BallFish CakeImitation Crab

Isinglass

Fish Gelatin

Cod

CodfishSalt Cod

Tuna

Tuna FishAlbacore TunaWhite TunaSkipjack TunaYellowfin Tuna

Salmon

Salmon ExtractSalmon Powder

Gelatin

GelatineBeef GelatinPork GelatinBovine GelatineFish GelatinMarine GelatinGelatine PowderE441INS 441441

A selection, not the full list.

Check a whole label at once

Recognising these by eye is the hard way to do it. Photograph the ingredients panel and NoshWise reads every line against this profile, names what to avoid, and says why.

Scan a label

Common questions

Are crab sticks fish or shellfish?

Fish. Crab sticks and seafood sticks are surimi, made from white fish, usually Alaska pollock. They are a real risk with a fish allergy and often not one with a shellfish allergy, though shellfish-derived flavourings are sometimes added, so the label still matters.

Is fish allergy the same as shellfish allergy?

No. They involve different proteins, parvalbumin in fish and usually tropomyosin in shellfish, and are separate conditions. Many people with one eat the other without difficulty.

Does Worcestershire sauce contain fish?

Traditional Worcestershire sauce is made with anchovies. It catches people out because it is used as a general savoury seasoning in gravies, marinades and drinks that contain no other fish.

What is dashi made from?

Most dashi is made from katsuobushi, dried fermented bonito, which is a fish. It is the stock base for miso soup, ramen broth, noodle dipping sauces and many instant seasoning powders, so a dish can appear entirely vegetable and still contain it. Kombu dashi, made from kelp alone, is the fish-free version.

Is gelatin a risk with a fish allergy?

Most gelatin is from pork or beef, but fish gelatin exists and is used in some products, including those aiming to be halal or kosher. A label reading only gelatin or E441 does not identify the source.