This study investigated the antioxidant and antimicrobial effects of nanoemulsions of orange, grapefruit, mandarin, and lemon essential oils on rainbow trout fillets stored at 4 +/- 2 degrees C in refrigerator. The results demonstrated that the shelf life of the rainbow trout fillets was determined as 10 days for the control group, 12 days for the tween 80 (surfactant), 14 days for orange and lemon treatment groups, and 16 days for mandarin and grapefruit groups. Nanoemulsions based on essential oils removed the fishy odor and had a positive effect on organoleptic quality. The use of citrus essential oil-based nanoemulsions decreased the values of biochemical parameters and slowed the growth of bacteria compared to the control group. Among all treatment groups, only the control group exceeded the TVB-N limit value on the 12th day of storage. PV and FFA values in fillets treated with mandarin and grapefruit nanoemulsions developed more slowly during the storage period. In addition, the lowest bacteria counts were found in the mandarin and grapefruit treatment groups. It can be concluded that especially mandarin and grapefruit EOs in all citrus essential oils can be recommended for preparing nanoemulsions in the preservation of rainbow trout fillets.