Mycomeal as a Functional and Sustainable Protein Alternative to Soybean Meal in Saline Tilapia Hybrid Fry ( Oreochromis spilurus ♂ × O. niloticus ♀) Diets

ABSTRACT This study examined how well mycomeal (rice bran fermented with Volvariella volvacea ) can serve as a sustainable replacement for soybean meal (SBM) in the diets of saline‐tolerant hybrid tilapia fry ( Oreochromis spilurus × Oreochromis niloticus, SpiN ) over a 60‐day feeding trial. Five isonitrogenous and isolipidic diets were formulated with graded levels of mycomeal replacing SBM (0%, 25%, 50%, 75% and 100%) and fed to triplicate groups of fish using a completely randomized design. Growth evaluation revealed that SBM can be fully replaced by mycomeal without compromising culture survival, growth, feed utilization or the proximate composition of SpiN . Nutrient analysis demonstrated that mycomeal has a higher apparent digestibility coefficient for protein (93.84%) than SBM (78.80%), but lower dry matter digestibility (72.00 vs. 91.10). Furthermore, mycomeal served as a functional feed ingredient, improving gut health and modulating the microbiota. Histological analysis revealed that 50% mycomeal replacement significantly increased intestinal villus length compared to the SBM control and other mycomeal‐based diets. This gut health improvement is also supported by a drastic increase in beneficial lactic acid bacteria (LAB) at the 75% inclusion level, while total bacterial count significantly decreased with mycomeal inclusion. Overall, mycomeal serves as an adequate and highly digestible protein source for saline‐tolerant hybrid tilapia fry. Its functional properties provide a strategic and sustainable solution for the continued expansion of tilapia aquaculture in saline and brackishwater environments.