Anomalous specimens of Rhamdia quelen (Siluriformes: Heptapteridae) and Gymnotus cf. sylvius (Gymnotiformes: Gymnotidae).

This article examines two cases of anomalous fish specimens found in freshwater habitats in Brazil. One case involves a Rhamdia quelen fish with tumors near its left pectoral fin, while the other case involves a Gymnotus cf. sylvius fish with a split caudal filament. The article provides detailed descriptions and illustrations of both cases and offers potential explanations for the anomalies. These findings contribute to our understanding of variations in the physical characteristics of fish species in the Neotropics. The article also includes acknowledgements and references for further research. [Extracted from the article]