Evaluating the efficacy of duckweed paste as a multifunctional organic binder in fish feed formulation

Abstract

This study explored the efficacy of two potential duckweed species (Spirodela polyrhiza and Lemna minor) as organic binders in fish feed as compared to traditional binders. Nine feeds including three control feeds—without binder (WB), cane molasses at 5% w/w (M5), and corn starch at 5% w/w (CS5)—and six experimental feeds—Spirodela paste feeds at 5% w/w (DWS5), 10% w/w (DWS10), and 15% w/w (DWS15) and Lemna paste feeds at 5% w/w (DWL5), 10% w/w (DWL10), and 15% w/w (DWL15)—were prepared and evaluated over a 360-day storage period in terms of water stability, sinking time, sinking time index, physical characteristics, nutritional composition, mineral content, microbial load, and spoilage. Duckweed-based feeds revealed significantly improved binding efficiency compared to control feeds. Notably, DWS15 appeared as most potent binder (followed by DWL15) with enhanced water stability (45.15–57.23%) and lower sinking time (2.14–2.44-fold) than WB, M5, and CS5, respectively. The feeds were found to be acceptable after overall evaluation of physical characteristics. Significantly higher crude protein content (27.77%) was recorded in DWS15, which was 11.44%, 8.99%, and 8.14% higher than CS5, M5, and WB, respectively. In contrast, the mineral content was significantly higher in DWL15. All duckweed binder feeds showed significant (p < 0.05) reduction in microbial load, aflatoxin, free fatty acids, peroxide values, highlighting their antimicrobial, antifungal, and antioxidant properties. Hence, the findings of the study revealed that duckweed paste of S. polyrhiza at 15% w/w followed by L. minor at 15% w/w served as cost-effective organic binders, offering substantial improvements in feed stability, protein content, and shelf life, making duckweed a valuable and sustainable alternative for enhancing fish feed quality and longevity.

Graphical Abstract