For a more specific treatment of an allergy it is important to know which allergen causes the allergy. The major fish allergen is a calcium-binding protein called parvalbumin that plays an important role in the majority of allergic reactions to fish. However, publications suggest that, beside parvalbumin, also other allergens of importance are present in fish. One aim of this Bachelor thesis is to identify and characterise such novel allergens in fish muscle of carp, tuna and cod. For this, extracts from muscle tissue of the three species were analysed in IgE immunoblots using sera from fish allergic patients. Except parvalbumin, protein bands of about 45 kDa showed high IgE-reactivity in all three fish extracts. The protein bands were cut out from Coomassie-stained SDS-PAGEs and were digested with trypsin for identification by mass spectrometry analysis. A search of the obtained mass spectrometry data against the protein database NCBI allowed to identify the 45 kDa protein as an enolase. For cDNA cloning of the enolase, RNA was isolated from tuna and carp muscle tissue and RT-PCRs were performed with tuna enolase-specific primers. Even though the cDNA cloning was not yet successful, the conditions for cloning were optimised and will form the basis for the production of recombinant tuna enolase. A second aim of the Bachelor thesis was the analysis of commercially available products of Melander regarding their allergenic potential. Melander, a hybrid of African and Asiatic wels, is a new fish on the market, which is regarded as a very healthy food source. So far, nothing is known about the potential allergenicity of this species and of products produced from Melander. Using immunoblots, Melander products were investigated regarding the presence of parvalbumin with parvalbumin-specific antibodies and regarding their allergenicity with sera from fish allergic patients. Surprisingly, although the Melander products had gone through several manufacturing processes, they showed high amounts of parvalbumin. Furthermore, patients displayed high IgE reactivity to the parvalbumins present in the Melander products and also to other proteins. Based on these data in can be concluded that Melander products, even though they are altered in taste, look and consistency, contain allergenic molecules, which can cause also severe symptoms in fish allergic individuals.