Growth Performance and Biochemical Profiles of Fairy Shrimp (Streptocephalus sirindhornae) Fed Natural Diets at Low and High Stocking Densities

This study investigates the growth performance, gut content composition, and biochemical profiles of the fairy shrimp Streptocephalus sirindhornae cultured with natural diets under low and high stocking densities (20 and 40 ind. L−1). Fairy shrimp were reared for 15 days in 1 m3 floating cages placed in earthen ponds. On day 15, individuals in the low-density treatment exhibited significantly greater body weight (0.074 ± 0.013 g) and total length (20.97 ± 0.90 mm) than those in the high-density group. A total of 54 food taxa were identified in the gut contents, with phytoplankton comprising the dominant fraction (91%). In contrast, 105 food taxa were recorded in the culture ponds, including 54 phytoplankton and 51 zooplankton taxa; chlorophytes (27 taxa, 50%) and rotifers (33 species, 63.46%) were the most diverse groups. Fairy shrimp feeding on natural pond foods exhibited high levels of essential amino acids, with monounsaturated fatty acids dominating and linoleic acid (C18:2n6c) representing the principal polyunsaturated fatty acid. Overall, the results indicate that low-density rearing enhances fairy shrimp growth, while the high diversity of natural food organisms contributes to the favorable nutritional composition of S. sirindhornae.