Feeding is one of the most important activities of fish (Fanta & Meyer, 1998). According to the nature of the food, the feeding activities of fish are classified into three categories: herbivores, carnivores and omnivores (Evans and Claiborne, 2006). In addition, fish are able to make choices regarding the preference of different type of food, and they may switch between feeding strategies according to the capacity of their anatomical and sensory structures (Fanta et al., 2001).A variety of feeding habits are found within fish family Anostomidae (Guisande et al., 2012), which contains 12 genera and 138 species that are widely distributed in Central and South America (Garavello & Britski, 2003). Half of these known species being found in the Amazon (Santos et al., 1996). The family includes fish popularly known as "aracus" or "piaus," which are characterised by their