Diet and morphological aspects related to feeding habit of two secies of Schizodon (Characiformes, Anostomidae) in the floodplain of the High Paraná River, Brazil

Abstract

The present research investigated the diet and its relations to morphological aspects of two "piavas", Schizodon borellii (Boulenger, 1900) and S. altoparanae Garavello & Britski, 1990. The individuals were collected with gill nets in the floodplain of the High Paraná River from March 1992 to February 1994. The dietary composition was determined using the frequency of occurrence method and points method (Hynes, 1950), and the feeding indices were calculated (Kawakami & Vazzoler, 1980). These indicates that the diet of the species was composed basically of Poaceae, grinded vegetal (originated from the grasses), and algae. This basic diet exhibited small temporal variation related to the fIood pulse, spacial variation and stage of development. Thus, the species were characterized as herbivore-grazers. The diet of the species showed relation to the morphology of the alimentary tract, especially the gut length and the structures used in the capture and ingestion of the food.