Food allergy, an adverse reaction to foods or food additives, affects around 5% of adults and 8% of children. Fish allergy is seen in 0.2% to 2.29% in the general population, and it differs according to regional dietary habits, fish species exposure and way of preparation and cooking. In children, it can represent a severe problem worldwide, and the prevalence has been reported between 0% and 7% worldwide. The clinical characteristics vary depending on the type of allergy (IgE-mediated or nonIgE-mediated) and range from mild symptoms to life-threatening anaphylaxis. Parvalbumins, enolases and aldolases are present in fish muscles, with the first been the major culprit allergen. A large cross-reactivity between different species of fish has been demonstrated. The protein β-parvalbumin, considered a pan-allergenic, is found in bony fish, while the non-allergenic α-parvalbumin is commonly found in cartilaginous fish. Based on this difference, as a first step in the therapeutic process of children with fish allergy caused by a certain fish in the bony fish category (i.e., hake, cod, perch, sardine, gilthead sea bream, red mullet, sole, megrim, sea bass, anchovy, tuna, swordfish, trout, etc.), an oral food challenge to an alternative from the category of cartilaginous fish is suggested (i.e., blue shark, tope shark, dogfish, monkfish, skate, and ray).