The schooling behavior of Astyanax altiparanae Garutti & Britski, 2000, was observed in a subtributary of the mid-Paranapanema River from January 1998 to February 1999. This species was shown to form two types of school: large schools, with approximately 50 individuals, were formed by smaller specimens located near the margin, around aquatic vegetation; and small schools (around 15 individuals), composed of larger specimens living preferentially in areas of deep water. Some behavioral variations in organization and localization were observed between these two groups, depending on the type of conducted activity, such as displacement frequency and foraging. The observed behavior of these schools when under threat underscores the idea that schooling is also an antipredation tactic.
Activity; behavior; fishes; lambari; Paranapanema river basin
