The Amazon region has the largest diversity of freshwater stingrays; however, there are still places where information about this group is scarce. The present work aims to record the occurrence of freshwater stingrays in the Uatumã river basin, Amazonas, Brazil. For this, collections were carried out in three municipalities bathed by the Uatumã River, Presidente Figueiredo, Itapiranga, and São Sebastião do Uatumã. The rays were collected through fishing using a hand net and, after capture, were identified through the pattern of the dorsal and ventral color of the disc, the absence or presence of the labial groove, and the organization of the row of spines on the tail, and were also measured, weighed, and sexed. In total, 69 specimens of Potamotrygonines were captured, 59 of which were from the genus Potamotrygon and ten individuals from the genus Paratrygon. The present study provides preliminary information on the characteristics of freshwater stingray species that may occur in the Uatumã River. Furthermore, new research is necessary to improve the identification of specimens to determine the diversity and elucidate aspects related to the biology of elasmobranchs in the Uatumã River Basin, Brazil.

Fish processing provides waste of around 50.0% to 70.0% of the animal's initial weight, especially the skin. Thus, this residue contains the by-product that allows biopolymers to be obtained, highlighting collagen, which can be widely used in different areas. The present study aimed to evaluate the yield of collagen extracted from peacock bass Cichla monoculus skin and to characterize them physicochemically. Twenty-five peacock bass with an average weight of 646 ± 175 g were used. The skin samples were removed by manual filleting and weighed, with an average yield of 3.7%. Subsequently, such models were analyzed for chemical composition, showing 61.8% for moisture, 29.3% for crude protein, 1.5% for ash, 6.3% for total lipids, and 1.2% for non-nitrogenous extract (NNE). Acid-soluble collagen (ASC) presented an average yield of 8.2%, presenting in its analysis of centesimal composition 12.5% ​​of moisture, 82.6% of crude protein, 1.1% of ash, 2.6% of total lipids, and 1.2% NNE. The skin and collagen extracted from the tucunaré skin have technological potential for use in the preparation of products, adding value to these by-products from fish processing.

Variação temporal e origem do Tambaqui (Colossoma macropomum) desembarcado na feira da panair / Temporal variation and origin of Tambaqui (Colossoma macropomum) disembarked at the panair fair

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 Potamotrygon orbignyi, Potamotrygon motoro, Potamotrygon scobina, Potamotrygon marquesi and specimens of the genus Paratrygon were identifield. Neonates and P. marquesi individuals were found was Itapiranga. At this stage, the blood profiles of P. orbignyi and P. scobina 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.