river due to siltation, pollution, and dam development. It may also be impacted by introduced species, such as tilapias,
peacock bass (Cichla) and Plagioscion squamossisimus (Alves et al., 2008; SoaresdaLuz et al., 2009). More research is urgently
needed to determine if this species is already locally extinct in the Rio das Velhas, located in the upper reach of Rio Sao
Francisco basin. The Rio das Velhas basin is a heavily populated region with high levels of pollution and frequent fish kills
(Alves and Pompeu, 2005).