Firm tofu, king oyster mushrooms, or suitable vegetables can provide alternative textures and flavors in place of fish. They are not nutritionally identical to fish and are not automatically safe for someone with allergies.
Allergen checks. Tofu contains soy; soy sauce contains soy and may also contain wheat. Check ingredients, allergen warnings, and preparation conditions. No warning does not guarantee the absence of cross-contact. Proper cleaning of utensils and surfaces that have touched fish, and separation during preparation, matter.
Replacing fish sauce. Soy sauce, mushroom stock, or a small amount of seaweed can supply a different umami flavor; choose according to the person's allergies. Fish and shellfish allergies are different; determine which seafood you can eat with your allergist.
Omega-3s. Flaxseed, walnuts, and chia supply plant ALA; the body's conversion of ALA to EPA and DHA is limited. Do not regard them as complete equivalents of the omega-3s in fish.
Cooking. Prepare tofu and mushrooms according to the product and recipe rather than applying one cooking time to all substitutes. If cooking fish, verify an internal temperature of 63 °C / 145 °F at its thickest point with a food thermometer.
This content is for informational purposes only and is not a substitute for medical advice. Consult your doctor before making decisions about your health.