Evaluation of Silkworm Pupae Meal and Fish Protein Hydrolysate as a Sustainable Fish Meal Replacement in Striped Murrel ( <i>Channa Striata</i> ) Diet: Impact on Growth Performance, Enzyme Activity and <i>IGF-1</i> Gene Expression

Abstract Silkworm pupae meal (SWP) and fish protein hydrolysate (FPH) are promising alternative protein sources due to their high nutrient availability and sustainability, which contribute to improved growth performance in aquaculture species. This study evaluated the effects of dietary SWP individually and in combination with FPH on growth, nutrient utilization, antioxidant capacity, digestive and metabolic enzyme activities, histology, hemato-biochemical profile, and growth gene expression ( IGF-1 ) of striped murrel ( Channa striata ). Fish were fed ad libitum with five experimental diets: control (35% fishmeal (FM)), 25 SWP (25% FM replaced with SWP), 50 SWP (50% FM replaced with SWP), 25 SWP+FPH (25% FM replaced with a combination of SWP and 3.5% FPH) and 50 SWP+FPH (50% FM replaced with a combination of SWP and 3.5% FPH). Each diet was fed to triplicate groups of 30 fish per cage for a period of 60 days, following a completely randomized design (CRD). Among the dietary groups, replacing FM with up to 50% SWP supplemented with 3.5% FPH (50SWP+FPH) diet did not negatively affect the growth performance and nutrient utilization efficiency in striped murrel. Additionally, fish fed a diet containing up to 50% SWP supplemented with FPH showed no negative effects on amylase, protease, and lipase activities, as well as in catalase (CAT), superoxide dismutase (SOD), villi length, and villi width compared to the control diet. However, no significant differences (P&gt;0.05) were observed in whole-body proximate composition, hemato-biochemical parameters, and the activities of glutathione peroxidase (GPx) and metabolic enzyme activities among fish fed different levels of SWP alone and supplemented with FPH diets. The relative mRNA expression of IGF-1 was significantly higher (P&lt;0.05) in fish fed the control and 50 SWP+FPH diets compared to other dietary groups. In conclusion, replacing 50% of FM with SWP supplemented with FPH is feasible and does not negatively impact growth, nutrient utilization, whole-body composition, digestive enzyme activities, intestinal histology, hematological and serum biochemical profiles, and IGF-1 gene expression in striped murrel ( C. striata ).