Phycoremediation of fish farming effluent with Scenedesmus acuminatus and use of the biomass in tambaqui (Colossoma macropomum) feed formulation

Aquaculture generates large volumes of nutrient-rich effluents that, if untreated, contribute to eutrophication. Microalgae-based phycoremediation offers a sustainable strategy to recycle these effluents while producing biomass of nutritional value. This study aimed to evaluate the production and nutritional composition of Scenedesmus acuminatus (SA) biomass cultivated in aquaculture effluent and to assess its inclusion in tambaqui ( Colossoma macropomum ) diets. The effluent was collected from intensive Brycon amazonicus tanks and used as the sole nutrient source for S. acuminatus cultivation in photobioreactors. Five isonitrogenous (32.2% crude protein) and isoenergetic (17.22 MJ/kg) experimental diets were formulated, including a control (SA0%) and four diets with increasing microalgal inclusion levels (SA1%, SA2%, SA3%, and SA5%). Juvenile tambaqui were fed these diets for five weeks, and growth performance, health parameters, and fillet nutritional composition were evaluated. S. acuminatus achieved consistent biomass yields with nutrient profiles comparable to conventional media. Its dietary inclusion did not compromise survival (100% across treatments), feed intake, or proximate composition of whole fish and fillets. Hematological analyses indicated immunomodulatory effects at higher inclusion levels, while fillet fatty acid profiles improved with increased omega-3 content, particularly at SA3%. These findings highlight the dual role of S. acuminatus in aquaculture effluent bioremediation and as a functional feed ingredient. The use of aquaculture effluents as culture medium supports circular bioeconomy principles and provides a sustainable alternative for the development of value-added aquafeed.