Utilization of Fermented Plant-based Proteins as a Sustainable Alternative to Fishmeal in Aqua Feeds: Effects on Growth and Immunity

Abstract

This study examines the potential of fermented plant-based proteins as sustainable alternatives to fishmeal in aquafeeds for Oreochromis niloticus (Nile tilapia), focusing on growth performance, immune function, and modulation of gut microbiota .A controlled 8-week feeding trial was conducted using five dietary treatments: a fishmeal-based control (FM) and four diets where fishmeal was partially replaced with fermented soybean (FSB), fermented lupin (FLP), fermented pea protein (FPP), or a mixed blend of fermented plant proteins (FMB). Results showed that tilapia fed the FSB and FMB diets exhibited significantly higher weight gain, improved specific growth rate (SGR), and reduced feed conversion ratio (FCR) compared to the control. Immune response markers, including serum lysozyme activity and respiratory burst, were notably elevated in these groups, indicating enhanced innate immunity. Gut microbiota analysis via 16S rRNA sequencing revealed increased alpha diversity and a higher relative abundance of beneficial bacterial genera such as Lactobacillus and Bacillus in fermented diet groups, while reducing potential pathogens like Aeromonas. These findings suggest that microbial fermentation improves nutrient availability, reduces anti-nutritional factors, and introduces probiotic effects that support fish health and performance. The study concludes that fermented plant-based proteins, particularly those derived from soyabeans and protein blends, are viable substitutes for fishmeal, offering nutritional, immunological, and microbial benefits. Their integration into tilapia diets can reduce reliance on marine-derived feed ingredients and promote environmentally sustainable aquaculture practices.