Abstract: To evaluate the effects of dietary coenzyme Q10 (CoQ10) on growth performance, body composition, antioxidant capacity, tissue structure and gene expression in juvenile genetically improved farmed tilapia (GIFT), juvenile GIFT tilapia with initial body weight of (19.97±0.13) g were fed with four diets containing 0, 40, 80 and 120 mg/kg CoQ10 for a 56-day trial. The results showed that the final body weight (FBW), feeding rate (FR), specific growth rate (SGR) and feed efficiency (FE) of supplemented CoQ10 groups had no significant difference compared with the control group, while 120 mg/kg CoQ10 group had the highest final body weight, specific growth rate and feed efficiency. The dry matter digestibility (DMD) of juvenile GIFT tilapia significantly increased when CoQ10 content was 120 mg/kg. The serum activities of catalase (CAT) and glutathione peroxidase (GSH-Px) in CoQ10 groups were significantly higher than those in the control group. The CAT and GSH-Px activities in liver of the CoQ10 groups were significantly higher than those in the control group. The SOD and GST activities in liver of 80 and 120 mg/kg CoQ10 groups were significantly higher than those in control group while malondialdehyde (MDA) content was significantly decreased. There was no significant difference in the moisture, crude protein and ash contents in the eviscerated whole fish among all groups. Compared with the control group, 120 mg/kg CoQ10 significantly decreased crude lipid content in the eviscerated whole fish. There was no significant difference in the moisture, crude protein, crude lipid and ash contents in the visceral mass among all groups. No significant histological changes in liver were identified in all groups. The intestinal villi length, villi density and muscle thickness in the 120 mg/kg group significantly increased. The expression of sod, cat, gsh-px, gst and igm mRNA in 120 mg/kg CoQ10 group were significantly higher than the control group, while the expression of il-1β and il-8 mRNA significantly decreased in the CoQ10 groups compared with the control group. In the challenge experiment by intraperitoneal injection with Aeromonas hydrophila, the cumulative survival rate of juvenile GIFT tilapia in 80 and 120 mg/kg CoQ10 groups was significantly higher than that in control group. In conclusion, these results suggested that dietary CoQ10 content within 120 mg/kg has no adverse effects on juvenile GIFT tilapia, dietary 120 mg/kg CoQ10 could improve digestibility, antioxidant abilities, liver antioxidant-related gene expression and resistance to Aeromonas hydrophila of juvenile GIFT tilapia.