The five species analyzed presented the same diploid number, 2n=48 chromosomes, but differed in karyotype formula. These results agree with the proposition that cichlids present a more conservative karyotype evolution and that the most frequent rearrangements appear to have been pericentric inversions and/or deletions. Only Crenicichla lepidota presented a multiple NOR system, indicating that the condition of a single nucleolar organizer is more primitive in this group. We may also state that constitutive heterochromatin seems to be highly conservative, with a preferentially pericentromeric pattern and with C-band positive NORs.