Balancing nutrition and health: effects of eri silkworm pupae meal inclusion on growth, serum biochemistry, and organ integrity in common carp

This study evaluated the potential of eri silkworm pupae meal (ESPM) as a fishmeal replacement in the diet of common carp (Cyprinus carpio). Eri pupae are nutrient-rich, containing 50–65% high-quality protein, a balanced amino acid profile, and beneficial omega-3 and omega-6 fatty acids, making them a promising sustainable aquafeed ingredient. Three dietary treatments were tested: (1) complete replacement of fishmeal with ESPM (ESPM 100%), (2) ESPM as the sole protein source with binder and filler (ESPM alone), and (3) a commercial feed (positive control). A total of 105 fingerlings (14–15 g) were distributed across treatments in seven replicates and reared for 10 fortnights. Growth parameters clearly indicated the superior performance of ESPM-based feeds, with ESPM alone showing the highest weight gain, specific growth rate, and relative growth rate, along with the lowest feed conversion ratio (p < 0.05). Muscle composition was also highest in ESPM-alone fish, with moisture (73.89 ± 0.22%), crude protein (26.45 ± 0.10%), fat (8.21 ± 0.82%), and ash (5.11 ± 0.66%). Essential amino acids followed the trend: ESPM alone > ESPM 100% >control. Serum markers (ALT, AST, HDLP and LDLP) showed no significant differences, though superoxide dismutase (SOD) was significantly higher in ESPM 100% (p < 0.001). Histopathology revealed normal hepatocytes and largely intact organ structures in ESPM 100%-fed fish, while ESPM alone showed mild alterations. Overall, ESPM proved to be a viable fishmeal alternative, enhancing growth and nutrient quality while maintaining physiological health in common carp.