Freshwater fishes are increasingly being considered threatened at regional (Bruton, 1990; Moyle, 1995; Fu et al., 2003) and international (Cambray & Giorgio Bianco, 1998) levels. In order to maintain their associated fishery resources, aquatic biodiversity, and the health of the systems which they inhabit, freshwater fish conservation has been recognised as an important action globally (Lowe-McConnell, 1990; Cowx & Collares-Pereira, 2002). A broad range of threats, which are mostly linked to anthropogenic impacts and biological invasions, increase the vulnerability of fishes (Bruton, 1995).