An 80-day feeding trial was conducted as two experiments to evaluate the effects of replacement of fish meal (FM) and soyabean meal (SBM) protein with hazelnut meal (HM) protein in the diets of mirror carp (Cyprinus carpio) fingerlings. Growth parameters and body composition were measured in fingerlings cultured under laboratory conditions in a recirculation system aquarium at 26 ± 0.3 °C. In Experiment I four isonitrogenous, isoenergetic diets were formulated by replacing 0, 25, 35 and 45% of protein from FM by HM. Fingerlings receiving the diets in which 0, 25 and 35% of the FM protein were replaced, had similar body weights, specific growth ratios (SGR), protein efficiency ratios (PER) and feed conversion ratios (FCR). In Experiment II four isonitrogenous, isoenergetic diets were formulated by replacing 0, 20, 40 and 60% of protein in SBM with HM. Fingerlings receiving the diets where 0, 20 and 40% of the SBM protein were replaced, had similar body weights, SGR, PER and FCR. However, fingerlings consuming the highest dietary inclusion level of HM (60% replacement) had significantly lower responses for all the above parameters than fingerlings receiving the other diets. The fat content of fingerlings fed diet FM3 where 45 % of FM protein was replaced by HM protein, was significantly lower than those on the other diets. It was concluded that HM could replace up to 35% of the protein in FM and 40% of protein supplied by SBM in fingerling carp diets without adverse effects on growth, FCR, PER, FI, BWG and body composition.