Abstract
This study reports the molecular identification of a tambacu-a hybrid of Colossoma macropomum and Piaractus mesopotamicus-in the floodplain of the upper Paraná River using molecular markers. The PCR-GEL method, based on the analysis of COI and TROP fragments, successfully characterized the hybrid, while PCR-SEQ, employing RAG2 and TROP markers, identified variable sites that differentiate the parental species and the hybrid.