Abstract: To investigate the effects of selenomethionine on growth performance and muscle tissue of Pelteobagrus fulvidraco, we formulated six experimental diets with selenomethionine as the Se sources. The supplemental levels of selenomethionine in the six experimental diets (S0, S1, S2, S3, S4, S5) were 0, 0.15, 0.30, 0.45, 0.60 and 0.75 mg/kg, respectively. The Se contents in diets were 0.17, 0.22, 0.29, 0.33, 0.41 and 0.45 mg/kg, respectively. The feeding experiment lasted for 10 weeks. The yellow catfish fed with S1 group feed showed the best growth performance and feed utilization rate, and had the most intact muscle histology. However, with the increase of selenomethionine levels in S1-S5 groups, the growth performance and feed utilization rate of yellow catfish decreased, the structural integrity of muscle tissue decreased, and the density and diameter of muscle fiber decreased and shortened, indicating that muscle tissue had been damaged. In addition, with the increase of dietary selenometine levels, the selenium content and the activities of antioxidant enzymes CAT, T-SOD and T-AOC in muscle tissue were increased. The mRNA expression of antioxidation-related genes (cat, sod1, sod2 and nrf2) and selenproteins (txnrd, sps2, gpx1, gpx2, msrb1, selenok and selenow) were significantly up-regulated, and the protein expression of NRF2 was significantly up-regulated. These results indicated that the antioxidant capacity and the expression level of selenomethionine in muscle of yellow catfish increased with the increase of dietary selenomethionine levels. Dietary supplementation of excessive selenomethionine can affect the growth performance of yellow catfish, reduce feed utilization, cause muscle tissue damage and reduce antioxidant capacity. This study determined that adding 0.15 mg/kg of selenomethionine to the diets of yellow catfish is most beneficial for its growth, and found that appropriate addition of selenomethionine can enhance the antioxidant capacity of P. fulvidraco muscles.