A 28-day growth performance trial was conducted to assess the potential of Eri Silkworm (ES) pupae as a partial or complete substitute for fish meal in Japanese quail (Coturnix japonica) diets. A comparative analysis of the nutrient, mineral, and essential amino acid composition of ES pupae, mulberry silkworm (MS) pupae, and fish meal was carried out. A total of 490 ten-day-old male Japanese quail, divided into seven treatment groups, each having seven replicates and 10 quails per replicate. The treatments included a control (without ES pupae), 25, 50, 75, and 100% ES pupae substitution, 75% MS pupae, and a commercial quail feed (positive control). The data on weekly body weight (WBW), body weight gain (BWG), feed intake, carcass weight, dressing percentage, and serum biochemical profile were collected. Results showed that 75% ES pupae meal significantly improved weight gain (p < 0.05) compared to commercial feed and MS pupae. The ES pupae exhibited superior nutritional profile, rich in essential amino acids (methionine, cystine, threonine, and lysine) and possessed higher fat content (24.36%) than fish meal and MS pupae. These findings suggest that ES pupae meal can replace up to 75% of fish meal in Japanese quail diets without compromising growth performance, offering a promising solution to reduce reliance on costly fish meal and promote sustainable poultry production.