Fish

What a fish allergy is

A fish allergy is a reaction to proteins in finned fish. The one most often involved, parvalbumin, is found across many species and survives cooking and canning well, so heat is no help. That is also why the labelling systems treat fish as a single category rather than species by species, even though individual sensitivities differ.

What makes fish difficult on a label is not chemistry but cuisine. Unlike milk or egg, fish is rarely fractionated into technical-sounding ingredients. Instead it is used as a background savoury note in products that do not present as fish at all: a dash of anchovy in a brown sauce, a spoon of fish sauce in a curry paste, a katsuobushi stock under a bowl of noodles. The fish is doing the work of salt, and nobody puts it in the product name.

The names that do not say “fish”

Anchovy is the alias that catches the most people. It is a defining ingredient of Worcestershire sauce, and therefore of anything made with Worcestershire sauce — including many brown sauces and marinades. Classic Caesar dressing contains anchovy, as do tapenade, puttanesca sauce, gentleman’s relish and some pizza toppings.

Fish sauce goes by nam pla in Thai, nuoc mam in Vietnamese and patis in Filipino. It is the backbone of South East Asian seasoning and turns up in curry pastes, dipping sauces and ready meals.

Bonito and katsuobushi are the Japanese equivalent: dried, fermented, smoked skipjack tuna, shaved into flakes. Dashi is the stock they are usually brewed into, under miso soup, noodle broths and a great deal of instant seasoning — but dashi is a category of stock rather than a fish product. Kombu (kelp) dashi and shiitake dashi contain no fish at all, and vegan versions are widely sold, so the word on its own does not settle it.

Surimi is white fish minced into a paste and shaped — most familiarly as crab sticks, which contain little or no crab. Kamaboko is the same material moulded into loaves.

Caviar, roe, ikura, tobiko and masago are fish eggs.

Isinglass is a collagen made from fish swim bladders, used to clarify some cask beers and wines. It is filtered out, and in the EU and UK it is exempt from declaration, so a beer clarified with it need not mention fish.

Omega-3 may be from fish oil or from algae; the label usually says which, but not always.

Gelatine is normally pork or beef, but fish gelatine exists and is used where pork and beef are unacceptable.

How the label is worded where you are

In the EU and UK, fish must be emphasised inside the ingredient list, so anchovy, bonito and surimi all have to carry the word fish. Two exceptions are named in the rules and are exempt from declaration altogether: fish gelatine used as a carrier for vitamin and carotenoid preparations, and fish gelatine or isinglass used as a fining agent in beer and wine.

The United States goes one step further than emphasis: FALCPA requires the species to be named, so the label reads anchovies or cod rather than fish. That is more informative but also means you are scanning for species names rather than one word. Elsewhere there may be no emphasis and no summary line, and a stock or sauce name may be all that is printed.

Cross-contamination and “may contain”

Fish cross-contact is mostly about shared cooking rather than shared factories. Fryers are the classic case — chips cooked in the same oil as battered fish — and so are grills, griddles, knives and counters in fishmongers, sushi bars and takeaways. Steam from cooking fish carries protein, which matters in small kitchens. Precautionary wording such as “may contain fish” is voluntary and unstandardised in most places, and no phrasing is legally safer than another; its absence is not evidence that no fish came near. Restaurant food, deli counters and loose items carry no ingredient list at all, so the question there is a spoken one. PNut reports any such wording as May contain rather than resolving it either way, and what “may contain traces” actually means explains why that is as far as any label lets you go.

Reading a fish label abroad

The word for fish is short and usually easy to find — pescado, poisson, Fisch, pesce, 鱼. The problem is that the fish in a product is often named as a species or a sauce instead. Acciughe, alici, anchoa, anchois, Sardelle and hamsi all mean anchovy and none of them contain the local word for fish. 鱼露 is fish sauce; nam pla and nuoc mam will be printed in Thai or Vietnamese script on domestic packaging. The table below gives the base word plus anchovy and fish sauce, which are the two aliases most worth recognising on sight; reading a label in a language you don’t speak covers how to work through the rest of the list around them.

How PNut flags fish

Scan the barcode and PNut looks the product up and reads its published ingredient list; photograph the ingredient panel instead and it reads the text off the label, in any of 40+ languages. It checks for fish and for every species name, sauce and stock alias on this page, then returns one of four verdicts — Safe, Contains allergen, May contain, or Unknown when the label cannot be read. It says Unknown rather than guessing.