Enhancing micronutrients bioavailability for tilapia reared in green water system using rice bran fermented with newly isolated phytase-producer, Pediococcus pentosacious, maintained both economic and environmental sustainability

The use of fermented plant waste as a functional feed ingredient remains a promising approach to enhance the nutritional value of aquaculture diets, boost fish health and growth, and support environmental sustainability. This approach tackles the challenge of reducing the high costs associated with conventional feed. This study investigates the effects of probiotic-fermented rice bran (FRB) on its composition, phytoplankton dynamics, Nile tilapia growth performance, and related biological and environmental parameters in green water system. FRB demonstrated increased total phenolic and flavonoid content, antioxidant activity, and amino acid concentrations while reducing antinutritional factors like phytic acid compared to unfermented rice bran. Inclusion of FRB in tilapia diets (30% and 50%) enhanced fish growth, feed efficiency, and skeletal development without inducing deformities. Phytoplankton analysis revealed dominance of Chlorophyta, particularly Chlorella vulgaris, in green water and fish gut, with significant microbial shifts favoring beneficial probiotics. Water quality indicators remained within optimal ranges, and FRB supplementation improved hematological parameters and reduced tissue degeneration. These findings highlight the potential of FRB as a sustainable feed component enhancing fish health, growth, and environmental stability.