This study aimed to investigate the effect of grape seed oil (GSO) on growth performance, feed utilization and the fatty acid profile of mirror carp fingerlings. Five isonitrogenous (36 g/100 g) and isoenergetic (3650 kcal/kg) diets supplemented with 0% (control), 0.5%, 1%, 2% and 3% of GSO were prepared. Three hundred fish (3.65 g) were randomly allocated in five trial groups in triplicate with 20 fish per aquarium and fed three times a day with experimental diets at satiation level for 84 days. Growth performance and feed utilization in fish were similar among all test groups, except for the GSO‐0.5 group. The condition factor, feed intake, hepatosomatic index, viscerosomatic index and proximate composition were not affected by GSO inclusion levels, except fatty acid profiles in fish flesh. The highest Σn3‐PUFA and Σn6‐PUFA values were observed in the GSO‐3 group, whereas this group showed the lowest atherogenic and thrombogenic index values compared with the other test groups. The ratio of hypocholesterolaemic/hypercholesterolaemic fatty acids in fish also increased by GSO inclusion levels. The results suggest that GSO supplementation up to 3% could improve fish flesh fatty acid profile and lipid quality without adverse effect on growth performance and feed utilization in mirror carp fingerlings.