Biochemical genetic characterization of F1 reciprocal hybrids between neotropical pacu (Piaractus mesopotamicus) and tambaqui (Colossoma macropomum) reared in Brazil

Abstract Electrophoretic profiles for pacu ( Piaractus mesopotamicus ), tambaqui ( Colossoma macropomum ) and their reciprocal hybrids `tambacu' and `paqui' are presented. Hybrids have been produced extensively in fishculture programs in Brazil and represent a potential threat to wild parental stocks, since approximately 4% of hybrid `tambacu' show zygotic sterility and/or low fertility. Diagnostic electrophoretic markers were based on three presumptive loci (EST*, SOD* and TF*) and four isohemoglobins. The markers can distinguish 100% of the F1 hybrids successfully. The efficiency of morphological characterization of pacu was equivalent to that obtained using electrophoretic methods (100%) but lower for tambaqui (98.8%), `tambacu' (98.7%) and `paqui' (82.6%).