Agricultural Research,Education and Extension Organization Iranian Journal of Fisheries Sciences 1562-2916 24 4 2025 07 01 Effects of fermented poultry waste with Saccharomyces cerevisiae on growth performance, survival, carcass composition, and selected immune parameters in juvenile Siberian sturgeon (Acipenser baerii) as a fishmeal replacement 747 756 133935 10.22092/ijfs.2025.133935 EN P. Salagh Department of Fisheries, Az.C., Islamic Azad University, Azadshahr, Iran. F. Ghojoghi Department of Fisheries, Az.C., Islamic Azad University, Azadshahr, Iran. A. Ghelichi Department of Fisheries, Az.C., Islamic Azad University, Azadshahr, Iran. S. Jorjani Department of Fisheries, Az.C., Islamic Azad University, Azadshahr, Iran. A. Seraj Department of Fisheries, Az.C., Islamic Azad University, Azadshahr, Iran. Journal Article 2025 07 01 In this study, 300 juvenile Siberian sturgeon with an average weight of 100.25±3.17 g were distributed in 12 fiberglass tanks (300 liters each) with a density of 25 fish per tank. Over 56 days, they were fed diets containing fermented poultry waste derived from <em>Saccharomyces cerevisiae</em> at 0% (control), 20% (T1), 30% (T2), and 40% (T3) as a replacement for fishmeal. The growth results showed that the final weight, weight gain, and specific growth rate increased significantly in T2 treatment compared to other treatments, especially the control group (<em>p</em><0.05). The lowest and highest feed conversion ratio was observed in T2 treatment (1.2±0.11) and the control (1.5±0.23) respectively (<em>p</em><0.05). The fish fed with T2 treatment showed the highest crude protein content (18.4±1.26) and the lowest crude fat content (1.35±0.29). However, there was no significant difference in the moisture and fat content between the different experimental treatments. The results indicate a significant difference in the levels of immunoglobulin IgM, respiratory activity (production of oxygen radicals), and serum lysozyme activity in the fish fed diet containing 30% treatment compared to other treatments, especially the control (<em>p</em><0.05). Overall, the addition of 30% fermented poultry waste from <em>S. cerevisiae</em> instead of fishmeal is recommended to maximize growth performance and improve the immune system. https://jifro.areeo.ac.ir/article_133935_cfc3466263410c8d938f6a9e443302ee.pdf