Evaluating morphometric variations in tocantins river fish: implications for conservation

The aim of this study was to characterize the fish species Triportheus angulatus, Psectrogaster amazonica and Pellona castelnaeana from the middle Tocantins River. Samples were collected from stretches of the Tocantins River, such as Cacauzinho and Beira Rio. Statistical program was used to evaluate seven variables from the three species under study, which were then classified according to their degree of correlation. According to Pearson's correlation analysis, the variables were significantly associated with the characteristics of the three species examined. The averages of the variables studied were highest for Pellona castelnaeana, and lower for Psectrogaster amazonica and Triportheus angulatus. Morphometric comparisons between males and females revealed statistically significant differences (p < 0.05) in total length and body depth, indicating potential sexual dimorphism related to ecological or reproductive roles. The condition factor (K) ranged from 1.28 to 1.65, reflecting a generally good nutritional status among individuals. Future studies focusing on the sex and age of fish are necessary to analyze how regional anthropogenic problems have influenced the morphometric characteristics of these species and to identify the factors that contribute to the decline in fish quality. These results could support future local and regional conservation efforts, considering that fishing in the region is economically and culturally important.