Valorizing Organic Waste Through Black Soldier Fly Larvae (Hermetia illucens): A Sustainable Solution for Aquafeeds with Key Nutrients and Natural Bioactive Polyphenols

Black soldier fly larvae (BSFL), Hermetia illucens, present a transformative approach to sustainable aquaculture and waste management by converting organic waste into nutrient-rich biomass. This study highlights BSFL-derived products as a sustainable alternative for aquafeeds, delivering essential nutrients and significant concentrations of bioactive and antioxidative polyphenols. We evaluated five organic waste types—Kitchen Waste (KW), Agricultural Waste (AW), Aquaculture Sludge (AS), Aquaculture Offal (AO), and a Mixed diet (MX)—assessing their impact on BSFL growth, Feed Conversion Ratio (FCR), bioconversion, Protein Efficiency Ratio (PER), survival, and nutritional composition, including Total Polyphenol Concentration (TPC). This is the first report to document and quantify the transfer of polyphenols from waste substrates to larvae, showing that larvae fed plant-based feeds contained significantly higher (5.8–7.4 mg GAE/100 g) TPC than those fed with an animal-based feed (0.60–0.9 mg GAE/100 g) (p < 0.05). Our findings emphasize the potential of BSFL to integrate waste valorization into circular economy frameworks, reduce organic waste, and enhance aquafeeds’ functional properties, contributing to ocean sustainability and the global transition to more sustainable aquaculture practices.