Effect of replacing fishmeal with spirulina ( <i>Arthrospira platensis</i> ) powder on growth, survival, body coloration, and meat quality in the freshwater prawn <i>Macrobrachium caementarius</i>

Abstract Microalgae are a valuable source of nutrients that are widely used in aquaculture to support the growth of aquatic species. This study aimed to assess the effect of replacing fishmeal with Spirulina powder ( Arthrospira platensis ) on the growth, survival, body coloration, and meat quality of Macrobrachium caementarius . We investigated the effects of diets containing different levels of fishmeal replaced by Spirulina powder: 0% (control), 25% (S25), 50% (S50), and 75% (S75), using 48 prawns during a 90‐day experiment. Our findings indicated that the experimental diets containing Spirulina did not significantly contribute to the growth of the prawns, although the survival rate remained high. The highest ( p &lt; 0.05) dry hepatosomatic indices were observed in the prawns fed the S25 (2.85%) and S75 (2.56%) diets. We noted distinct color differences based on the diet: prawns fed the S25 exhibited a yellow‐orange color, while those on the S50 and S75 diets developed a red‐orange hue. Prawns of the S75 diet had significantly higher ( p &lt; 0.05) numbers (239.00/mm 2 ), indices (4.76), and coefficients of chromatophores (95.20). Prawns fed the S50 and S75 diets showed higher protein content but lower lipid levels compared to the control diet. Our findings highlight the potential of Spirulina powder to replace fishmeal in diet formulations without compromising prawn M. caementarius performance. Diets containing 50% and 75% Spirulina powders are recommended as a fishmeal substitute. These results could contribute positively to the developing aquaculture sector for this valued species.