AbstractA 10‐week feeding trial aimed to investigate the effects of dietary vitamin C (l‐ascorbic acid) on growth, antioxidant activity, and immunity in ricefield eel, Monopterus albus. Six diets were formulated with different levels of vitamin C supplementation (0.1, 17.5, 34.8, 68.6, 139.7, and 278.5 mg/kg). The results indicated that the weight gain (WG) of the M. albus fed the diets with vitamin C was remarkably higher than that of the M. albus fed the control diet (p < .05), and the quadratic analysis showed an optimal vitamin C lev...