[2] This group has a very ancient divergence from the rest of the Characiformes, dating back to the Early Cretaceous or earlier, and it has been suggested that it be better treated as its own order, the Cithariniformes.

[4] The Characiformes likely first originated and diversified on the supercontinent of West Gondwana (composed of modern Africa and South America) during the Cretaceous period, though fossils are poorly known.

[1] During the Cretaceous Period, the rift between South America and Africa would be forming; this may explain the contrast in diversity between the two continents.

[4] Previously, the oldest characiform was assumed to be Santanichthys of the Early Cretaceous (Albian Age) of Brazil.

[7][8] Uniquely, Late Cretaceous characiform fossils are found significantly north of their modern distribution.

Indeterminate characiform teeth are known from the Santonian of Hungary and Maastrichtian of France, which have a large, multi-cusped appearance reminiscent of African alestids.

The smallest in size is about 1.7 cm (0.67 in) in the Bolivian pygmy blue characin, Xenurobrycon polyancistrus.

The red-bellied piranha, a member of the family Serrasalmidae within the Characiformes, is endemic to the Neotropical realm.

Many species commonly called tetras are popular in aquaria[16] because of their bright colors, general hardiness, and tolerance towards other fish in community tanks.