The increasing spread of invasive alien species (IAS) in freshwater ecosystems poses major ecological challenges while generating large amounts of biomass through mandatory eradication and control programs. The CIRCOLACQUA project funded by the Italian Ministry of Health (IZS PLV 09/22 RC, CUP: J19I22001180001) proposes an integrated circular economy approach aimed at transforming this management issue into an environmental and economic opportunity. Focusing on two widespread freshwater IAS, the European catfish (Silurus glanis) and the red swamp crayfish (Procambarus clarkii), the project explores their dual role as indicators of aquatic pollution and as alternative raw materials for aquaculture feeds.

The first component of the project investigates the suitability of both species for environmental monitoring by assessing the accumulation of multiple contaminant classes, including trace elements, rare earth elements, persistent organic pollutants, pesticides and microplastics. Their widespread distribution, high biomass availability and mandatory removal make these species promising organisms capable of providing information on ecosystem contamination while avoiding impacts on native fauna.

The second component evaluates the valorization of IAS biomass as a sustainable protein source for aquaculture. Experimental diets containing 20% S. glanis or P. clarkii meal were tested in rainbow trout (Oncorhynchus mykiss), demonstrating good nutritional quality, absence of antibiotic residues, normal growth and physiological performance, and no evidence of adverse histological or oxidative stress effects. These findings support the feasibility of incorporating IAS-derived ingredients into aquafeeds within a circular economy framework. Overall, CIRCOLACQUA demonstrates how invasive species can simultaneously support environmental pollution monitoring and sustainable biomass valorization, contributing to biodiversity conservation, waste reduction and the development of innovative management strategies aligned with the principles of One Health and the circular economy.