Segregation in the use of the water column by two congeneric species of Characidae, Hyphessobrycon bifasciatus and H. luetkenii, was investigated through underwater observations in the Cabiúnas coastal lagoon in northeastern Rio de Janeiro, Brazil. The use of the water column by the two species differed significantly. Hyphessobrycon luetkenii occupied mainly the uppermost stratum, with 79% of the observations within 20 cm of the surface; whereas H. bifasciatus was more common between 20 cm and 40 cm below the surface (55% of the observations). Predation pressure, macrophyte cover and nutrient distribution may influence this vertical segregation.
Habitat use; Spatial segregation; Underwater observations; Restinga de Jurubatiba National Park
