Physiological parameters of freshwater stingrays from the Uatumã River Basin, Amazon, Brazil

Knowledge of freshwater stingrays' physiological parameters is essential for conserving elasmobranch diversity. This study aims to characterize the erythrogram and plasma biochemistry of freshwater stingrays from the Uatumã River basin for the first time. Specimens were captured in Presidente Figueiredo, São Sebastião do Uatumã, and Itapiranga, Amazonas, Brazil. Blood samples were collected from 69 stingrays and processed to obtain blood values. The species <italic>Potamotrygon orbignyi</italic>, <italic>Potamotrygon motoro</italic>, <italic>Potamotrygon scobina, Potamotrygon marquesi</italic> and specimens of the genus Paratrygon were identifield. Neonates and <italic>P. marquesi</italic> individuals were found was Itapiranga. At this stage, the blood profiles of <italic>P. orbignyi</italic> and <italic>P. scobina</italic> rays were lower than those of young, adult, and subadult individuals. The results were similar across locations, species, and existing data from the Amazon basin. The study provides a basis for future research on stingrays in the Uatumã River basin.