This family contains many headstanders, which habitually swim with their heads pointing from 45° up to 90° downwards; most feed on plants near the bottom, while others also eat detritus and invertebrates picked up from river- or lakebeds.

Anostomidae are generally considered edible, and some of the larger species are caught for food on a regular basis, much like large Leuciscinae (which are superficially similar Cypriniformes) are in the temperate Northern Hemisphere.

[3] Their jaws are rather short, with the maxillary bone small and excluded from the mouth opening, while the ascending process of the premaxilla is triangular in overall shape and robustly developed.

Leporellus has long been recognized as the basal-most living anostomid genus, due to its many plesiomorphies shared with the Chilodontidae and its peculiar apomorphies, and separated as a monotypic subfamily by some.

[1] But the latter view is incorrect, as it includes a large number of lineages that are really basal members of the family and should not be treated as a subfamily (except monotypic ones, but these are generally avoided).

For one, the biogeography of the family, with some very basal taxa found west of the Andes, indicates it was already well distinct when the northern part of that mountain range uplifted at the end of the Middle Miocene about 12 million years ago (Mya).

Whether the family originated in Oligocene or already in the Eocene (or perhaps even in the Paleocene) cannot be said until more fossil material is recovered, either to answer this question directly or to provide calibration for molecular phylogenetic studies.