The fish Psectrogaster amazonica Eigenmann & Eigenmann, 1889 (Characiformes: Characidae), known locally as “branquinha” in the Tocantins region of Maranhão, is a freshwater species found in the Tocantins River, Brazil. The main objective of this study was to conduct an osteological analysis using anatomical techniques to better understand biodiversity and enable more detailed investigations. Five osteological methods were tested to assess preservation, practicality, and efficiency: immersion in glycerin, immersion in hydrogen peroxide, dissection, dissection with hot water, and burial. The results indicated that immersion in hydrogen peroxide and dissection with hot water were the most effective methods, facilitating the removal of soft tissues and preserving bone structures. Glycerin preserved the structures well but made dissection more difficult. Hydrogen peroxide, after thre...