Replacement of fish meal with economic alternative ingredients in aqua-feed is one of the most important question in aquaculture in the past four decades. In this paper, we evaluated the potential of replacing fish meal with feather meal in large yellow croaker (Larimichthys crocea) diet, with emphasis on the roles of keratinase DP-100 and gamma irradiation to improve feather meal use in fish diets. We used a two-way experimental design. A diet containing 35% fish meal severed as basal diet (BD), and 30% of fish meal in diet BD was replaced with hydrolyzed feather meal (I0E0). In diet I0E0, 1% keratinase DP-100 was added (I0E1), or the hydrolyzed feather meal was replaced with gamma ray (γ) irradiated feather meal (I1E0), or 1% DP-100 supplementation and replacement of the hydrolyzed feather meal with γ-irradiated feather meal were performed in combination (I1E1). Large yellow croaker were fed with the test diets in experimental net pens (1 m×1 m×2 m) for 10 weeks. Initial body weight of the test fish was (19.7±0.2) g (±SD, n=15), and fish density was 40 fish per pen. The results showed that 1% DP-100 supplementation significantly affected (P＜0.05), while γ-irradiation did not obviously affect (P＞0.05), feed intake, final body weight (FBW) and weight gain. Feed conversion ratio (FCR), nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE), energy retention efficiency (ERE), condition factor, hepatosomatic index, viscerosomatic index, whole body composition, ratio of fish meal consumption to fish production (RCP), nitrogen waste and phosphorus waste were independent on DP-100 supplementation, γ-irradiation and their interactive effect (P＞0.05). The feed intake, FBW and weight gain were higher in fish fed diets I0E1 and I1E1 than in fish fed diets I0E0 and I1E0 (P＜0.05). The FBW and weight gain of fish fed diet BD was higher than those of fish fed diets I0E0 and I1E0 (P＜0.05), but did not significantly differ from those of fish fed diets I0E1 and I1E1 (P＞0.05). The RCP was lower in fish fed diets I0E0, I1E0, I0E1 and I1E1 than in fish fed diet BD (P＜0.05), while no significant differences were found in FCR, NRE, PRE, ERE, condition factor, hepatosomatic index, viscerosomatic index, whole body composition, nitrogen waste and phosphorus waste between fish fed diet BD and diets I0E0, I1E0, I0E1 and I1E1 (P＞0.05). This study indicates that 1% DP-100 supplementation benefited to improve feather meal as a fish meal substitute in large yellow croaker diet, while γ-radiation treatment did not play a positive role in increasing fish meal replacement level with feather meal. Dietary fish meal level for large yellow croaker could be reduced from 35.0% to 24.5% by adding 1% DP-100 and 8.5% hydrolyzed feather meal in combination.