Where is fish found?
Fish muscle is eaten cooked, fried, pickled, and raw, but fish eggs, caviar, skin, gelatin, and blood also have provoked fish allergy symptoms. Plus, fish and fish based gelatins and collagens can be unexpected ingredients in a host of foods and nonfood items, such as pharmaceutical gel capsules and vaccines.1 And while fish is identified on most food labels, if fish is part of an oil, it may not be listed.3
On food labels, fish may be identified as such or may be listed as any of the following:6 anchovies, bass, catfish, cod, flounder, grouper, haddock, hake, halibut, herring, mahi, perch, pike, pollock, salmon, scrod, sole, snapper, swordfish, tilapia, trout, and tuna.
Foods that may contain fish proteins include:6,7 barbecue sauce, bouillabaisse, Caesar salads and dressings, caponata (a Sicilian eggplant relish), etouffee, fish oil, fish sauce, fish sticks, fritto misto, gelatin (often made from fish skin and bones), gumbo, imitation or artificial fish or shellfish (e.g., surimi, sea legs, sea sticks), jambalaya, kedgeree (a fish and rice dish), paella, stocks, soups, and Worcestershire sauce.
Unfortunately, there's a high risk of cross-contamination in food prep areas, and as such, it may be best to avoid all seafood restaurants, even if you plan to order something other than fish.5 Also be wary of restaurants with African, Chinese, Indonesian, Thai, and Vietnamese cuisines, which regularly incorporate fish, as the risk of cross-contamination is high in these environments.6 This hazard also extends to frying oils. For example, if French fries (chips) were fried in the same oil as fish, the oil could contain traces of fish proteins, which may be passed along to the French fries.7 Also be wary of filleted fish. According to a recent investigation, supermarkets and restaurants may substitute cheaper fish varieties for more expensive types since many fish species look similar once filleted. For example, an establishment might list an item as red snapper when in fact it might be tilapia. So it's critical to explain your fish allergy to anyone handling your fish to ensure you receive the species you're expecting.5
Since it's possible to be allergic to fish gelatin, which is derived from fish skin and bones, you could also react to dietary supplements containing fish oil.5 This oil may be included in items such as cosmetics, toiletries, medicines, and bath and massage oils. And although research hasn't definitively identified omega-3 supplements derived from fish as known allergen triggers, it's still safest to avoid any such products if you are allergic to fish.7 If your allergy is severe, you may react to the vapor or steam present in environments where fish is being cooked. As a result, allergic reactions among workers in the seafood industry are common and include occupational asthma, contact rashes, allergic rhinitis (aka hay fever), and conjunctivitis (aka pink eye).7