摘要
The purpose of this paper is looking for associations between environmental factors and morphological parameters in tambaqui （Piaractus brachypomus） individuals to differentiate this species in lentic environments （lake） and lotic （river）. In this, regard studied 30 specimens, 15 from lentic environment （lake） and 15 from lotic （river）. Also, on right profile of these 25 morphometric variables were measured. On data matrix a PCA （principal components analysis） based on morphometric correlations matrix, which was defined in the new morphologic space of these specimens （3 principal components） which explain 73.23% of variability. Fish projection in first two principal components showed a morphological differentiation between two environments （lentic and lotic）, with variables as, horizontal eye diameter, length maxilla, suggesting greater response of these fish in lotic environment by their adaptation to light conditions, predators threat and food distribution. Finally, in lotic environment these fish have thinner caudal peduncle, indicating greater plasticity, namely stylized fish.
