Within this clade, it is considered a part of the "Pimelodus-group" of Pimelodids, which also includes Pimelodus, Exallodontus, Duopalatinus, Cheirocerus, Iheringichthys, Bergiaria, Bagropsis, Parapimelodus, Platysilurus, and Platystomatichthys.

[4] P. caesius is also found in many of these regions, with tributary range including Tocantins, Pará, Jari, Xingu, Trombetas, Madeira, Negro, Purús, Japurá, Juruá, and Içá rivers.

As in other pimelodids, these whiskers are extremely long; the maxillary barbels extend past the base of the caudal fin.

[2] Propimelodus lives in swiftly flowing waters of open channels of the Amazon River and many of its large tributaries; P. caesius is one of the most common fish in these habitats.

[2] P. eigenmanni is nocturnal, found in tidally influenced freshwater habitats on mud substrate and near dense vegetation.