Duckweed as a sustainable alternative protein source for extruded aquafeed production

IMPRESS Practice Abstract No. 05 Background/Problem: Aquafeed producers need sustainable alternatives to conventional protein sources, including soybean meal. Duckweed is a fast-growing aquatic plant with potential to provide a resource-efficient and environmentally sustainable protein ingredient for aquafeeds. Practice Change: The IMPRESS project evaluated the use of Lemna minor and Landoltia punctata duckweed biomass in extruded feeds for golden grey mullet (Liza aurata) at inclusion levels of 10% and 20%. Evidence & Outcomes: Duckweed-containing feeds maintained comparable nutritional quality to conventional feeds and were successfully produced by pilot-scale extrusion. Feeds containing Lemna minor required less mechanical energy during processing, indicating improved manufacturing efficiency. The best balance was observed at 10% Lemna minor inclusion, where improved processing behaviour was combined with satisfactory pellet water stability. Conclusion: Duckweed is a technically feasible and sustainable protein ingredient for extruded aquafeeds. At moderate inclusion levels, particularly 10% Lemna minor, it can support sustainable feed production while reducing reliance on soybean-based ingredients.