The Proximate Composition, Amino Acid Profile, Fatty Acid Content, and Mineral Content of Scale Flour from Three Fish Species as Potential Feeds for Fish Fry

<b>Background</b>: Fish scale waste is highly valued both as a food additive and as a functional food ingredient. This study aimed to analyse the chemical composition, fatty acid profile, and mineral content in fish scale flour of Osphronemus (O) goramy, Cyprinus (C) carpio, and Oreochromis (O) niloticus as potential feed for fish fry.<b>Methods:</b> Fish scales were cleaned with 10% w/v NaCl solution at a ratio of 1:10 (w/w) for 24 hours at 4 °C. Agitation was used every eight hours to remove excess protein. Fish scales were evenly arranged in a cooker and cooked at 121 °C for 10 minutes with 15 psi pressure. After cooking, 100 grams of wet fish scales was dried at 50 °C for four hours. Dried fish scales were processed into flour for analysis of chemical composition, amino acid content, fatty acid content, and mineral content.<b>Results:</b> Significant content differences were observed for most chemical components, amino acids, and minerals (p&lt;0.01) in the examined fish scale flour of three fish species, with the crude protein content ranging from 49.52% to 72.94% and the fat content ranging from 0.11% to 0.23%. The magnesium mineral content varied between 767.82 and 816.50 mg/kg, while the calcium content ranged from 3.54 to 12.16 mg/kg. The iron content was within the interval of 40.46 to 44.10 mg/kg, and the zinc content exhibited variability ranging from 45.80 to 139.19 mg/kg. Glycine was the predominant free amino acid (FAA) across all species, with concentrations varying from 13.70% to 16.08%, while histidine had the lowest content, ranging from 0.39% to 0.71%. Conversely, the fatty acid content was lowest among the three species, ranging from 6.73% to 9.48%.<b>Conclusion:</b> Scale flour from three farmed fish types showed potential for fish fry feed due to its chemical composition and amino acid and mineral contents. To enhance the essential fatty acid content, enriching the flour with oils containing eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and α-linolenic acid (ALA) is essential.