Aquaculture now supplies over half of the fish consumed globally, positioning it as a critical solution to meet rising protein demand. However, its expansion is constrained by limited availability of high-quality feed ingredients, such as fishmeal. As this ingredient becomes increasingly strategic, the sector must explore alternatives that fulfill nutritional requirements while maintaining fish robustness under modern feed formulation scenarios.
The Pep4Fish project developed and evaluated protein hydrolysates (PHs) derived from Hermetia illucens larvae and animal by-products – including fish by-products from processing and canning industries, and swine by-products from slaughterhouses - as functional aquafeed ingredients. These PHs, rich in bioactive peptides and produced from upcycled raw materials, align with circular economy principles. Several feeding trials were conducted with European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) using practical feed formulations currently used by the industry.
Among the tested PHs, swine-derived hydrolysate showed the highest potential, maintaining feed intake, macronutrient digestibility, and whole-body composition, even when replacing high-quality fishmeal and a commercial fish hydrolysate. Effects on growth and somatic indices were formulation-dependent. Altered lipid metabolism emerged as a key physiological response to both dietary composition and environmental stressors.
These findings support the inclusion of hydrolyzed Hermetia illucens larvae and animal by-products as functional ingredients in aquafeeds, contributing to waste valorization, reduced reliance on marine resources, and enhanced sustainability of aquaculture systems.
Acknowledgments: This work was supported by the Blue Bioeconomy Pact (C644915664-
00000026), for the exercise of activities in the WP6 FEED (Pep4Fish project) through
international funds provided by the European Union. AAO, AC and LRS acknowledge FCT for their PhD grants (2023.02611.BD; 2023.00947.BDANA; 2024.00449.BDANA).