Most food allergies become apparent in early childhood, but fish allergy takes time to develop and generally shows up in adulthood. It is one of the most common food allergies. However, if you are allergic to one kind of fish, it does not necessarily mean you are allergic to all the other kinds. A codfish allergy occurs due to the IgE antibodies present in the fish. Your immune system assumes that fish is a foreign invader, dangerous for your body and reacts poorly to it. The symptoms of fish allergy may range from mild to extreme, depending on the severity of the allergy. The most common signs that you may notice are: Skin rash or hives Stomach cramps Nausea Diarrhoea and vomiting Indigestion Sneezing Runny or stuffy nose Asthma Headaches Anaphylaxis or anaphylactic shock, wherein your body undergoes a fatal reaction, impairing your breathing and rendering you in shock There is a considerable difference between having a fish allergy and being intolerant to fish consumption. The former could be life-threatening, while the latter might cause you to experience specific mild symptoms. You must connect with a healthcare practitioner to ensure that your symptoms indicate a fish allergy. They will likely conduct a skin-prick or blood test to diagnose the fish allergy. In the former test, your doctor will administer or prick a small amount of protein-containing liquid from the fish in your forearm or back. If it causes your skin to react, leading to a reddish bump, the fish allergy is confirmed. A blood test is relatively simple, where the doctor tests your blood to see if there is any presence of IgE or immunoglobulin antibodies against the fish proteins or allergens. If the IgE antibody levels are high, it may indicate a fish allergy. Apollo 24|7 offers a quick, effortless and at-home fish allergy test which can help: Determine whether you have a fish allergy. Establish if the allergy is specific to cod fish. Detect the severity of the fish allergy. Devise an effective treatment plan to help treat fish allergy and its symptoms. Once the tests confirm the fish allergy, your doctor will help you determine the management plan. For instance, you would have to consult your allergist first before eating a particular type of fish. Also, make sure not to consume fish that has come in contact with other fish you are allergic to. Moreover, read the labels of products carefully and be cautious when eating out in a restaurant. Apollo 24|7 offers a comprehensive fish allergy test to detect fish allergy in patients.   Medically reviewed by Dr Jatin Ahuja, Infectious Diseases, Apollo Hospitals Indraprastha, South Delhi.