Abstract: The effects of methanotroph (Methylococcus capsulatus, Barh) bacteria meal (MBM, FeedKind^®) replaces fishmeal (FM) on the growth performance and antioxidant capacity of Trachinotus ovatus (initial mean weight 34.88±1.13 g) were conducted through a 56-day breeding trial. MBM at 0, 3%, 7% and 10.5% were added to replace fishmeal at 0, 10%, 20% and 30%, to formulate four isonitrogenous and isolipidic feeds named MBM0, MBM10, MBM20 and MBM30, respectively. The results of the experiment showed that there was no significant difference in the final mean weight, weight gain rate, specific growth rate, survival rate, hepatosomatic index, visceral index and feed factor between the groups as the MBM content in the diets increased (P>0.05). The condition factor of the MBM30 group was significantly higher than that of the MBM0 group (P<0.05). The crude protein content of whole fish in each group was not significantly different (P>0.05), while the crude fat content of whole fish in the MBM20 group was significantly higher than that in the MBM0 and MBM10 groups (P<0.05). The crude fat content of dorsal muscle in the MBM20 and MBM30 groups was significantly higher than that in the MBM0 group (P<0.05), and there was a significant positive correlation between the crude fat content in dorsal muscle and the proportion of fishmeal replaced by MBM (P<0.05). Serum triglycerides were significantly lower in the MBM20 and MBM30 groups than those in MBM0 group (P<0.05), serum glutathione transaminase activity was significantly higher in the MBM20 group than that in the MBM0 group (P<0.05), and serum albumin was significantly higher in the MBM10 group than those in MBM0 group (P<0.05). Total serum antioxidant capacity in MBM20 group was not significantly different with the MBM0 group (P> 0.05), while significantly higher than that in the MBM10 and MBM30 groups (P<0.05). Intestinal superoxide dismutase activity in the MBM20 group was significantly higher than that in the rest of the groups (P<0.05). Vacuolar area in liver through H&E-stained was significantly higher in the MBM20 and MBM30 groups than that in the MBM0 group (P<0.05). In conclusion, at 35% fishmeal content in the basal diet, MBM could replace 20%—30% of fishmeal without negatively affecting growth performance, morphological indices, body composition and serum biochemical indices of Trachinotus ovatus.