Tilapine species, the most widely distributed exotics within the state, have had negative impacts on fisheries and on fish species compositions in reservoirs. fasciatum in areas where only the first species naturally occurs. Genetic problems can also be foreseen with the release of hybrids of Pseudoplatystoma corruscans and P. The widespread introduction of the peacock bass and other piscivorous species is the cause of local extinctions in the central lake of Lagoa Santa and in the Rio Doce valley lakes. The recent introduction of Leporinus macrocephalus from the Pantanal may cause the same impact to the native L. eques, can be captured from the same water body and the non-native species can be much more abundant than the native species. Congeneric species, such as Hyphessobrycon bifasciatus and the exotic H. In some of the most important river basins of that state, alien fish species might represent up to 40% of the fish fauna. In Minas Gerais, Brazil, records of exotic species have increased over the past seven years. The few recorded benefits of non-native species introductions are restricted to the improvement of fish production and sport fisheries. Known impacts of exotic fishes include native species extinction, changes in competition and predation rates, limnological perturbations, introduction of diseases and parasites, hybridization with native species, and changes in fisheries composition. In Brazil, despite federal and state regulations, there are misunderstandings about such concepts as native, exotic, allochthonous, or autochthonous fishes and introductions, translocations, reintroductions, and transfers of fishes. Accidental escapes also contribute significantly. There are many reasons for introductions: reservoir stocking programs, aquaculture, sport fishing, control of disease vectors, and the pet trade. For some time, the rate of non-native fish introductions has been increasing in South America.
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