The difficulty in identifying some species of Lambaris comes from very similar phenotypic feature that often result from hybridization. The parasites can be indicative of various aspects of the biology of their hosts, including phylogeny, because some groups of parasites may have host specificity. The objective was to evaluate the genetic diversity and parasitology of the fish Astyanaxaff.bimaculatus. in ponds and streams adjacent to fish farms located in the Lower São Francisco, Sergipe, Brazil. The specimens were collected in the municipalities of Propriá and Neópolis and necropsied in the search for metazoan parasites. Sections of muscle tissue were taken for DNAextraction. The samples were subjected to PCR and electrophoresis with the products of the reactions. Subsequent cluster analysis was performed. Atotal of 102 fish were infected with Lernaeacyprinaceaand Dolopssp. on the bo...