Evaluating the Impact of Black Soldier Fly (Hermetia illucens) Larvae Meal on Growth Efficiency and Feed Utilization in Rainbow Trout (Oncorhynchus mykiss) Juvenile

Aims: Black Soldier Fly (BSF) larvae meal is a promising alternative protein source in aquafeed, offering high nutritional value and essential amino acid profiles like fishmeal. Nepalese Rainbow trout (Oncorhynchus mykiss) farming currently relies on imported shrimp meal, presenting economic and ecological challenges. The focus of this research was to examines the potential of BSFL meal to replace the shrimp meal in trout feed. Place and Duration of Study: Fisheries Research Station (FRS), Trishuli Nepal, between May 1 to August 7, 2023. Methodology: A feeding trial was conducted using 750 healthy Rainbow trout (mean individual body weight 5.39±0.55 g) randomly divided into five experimental groups, each having three replicates. The control diet contained no BSFL meal (CON), while experimental diets replaced 25% (BSF25), 50% (BSF50), 75% (BSF75), and 100% (BSF100) of shrimp meal with BSFL meal. Fish were raised in flow-through raceway tanks (300L) and fed twice daily until satiation. The growth efficiency parameters were measured. Results: The results demonstrated that diets with 25-50% BSFL meal substitution (B25, B50) significantly enhanced growth efficiency compared to the control, reflected in higher final body weight and weight gain, and improved feed conversion ratios (P<0.05). Conversely, higher replacement levels (75% and 100%) negatively impacted growth, possibly due to increased chitin content affecting digestibility. Statistical analysis confirmed the optimal BSFL inclusion range for growth efficiency, with specific growth rates peaking in the B50 group. Conclusion: In conclusion, BSFL meal can effectively replace 25-50% of shrimp meal in rainbow trout feed, offering a viable and sustainable protein source for trout farming in Nepal. This substitution could reduce dependency on imported shrimp, promoting more sustainable practices.