Human populations inhabiting the Amazon Basin depend on large amounts of fish in their diets to meet their protein demands. It is vital to manage this valuable resource not only for its intrinsic value but for its significant extrinsic value to humans and the entire Amazon ecosystem. The present study contributes new information on the biology of two common Amazonian fish species. The relationship between the weight and length of Serrasalmus rhombeus (Piranha Blanco) and Potamorhina latior (Llambina) from three oxbow lakes is examined, and how different habitat types influence fish...