There are tens of species of small fish called the Darter Characin, all characins from South American freshwater and most quick darting, bottom-dwelling fish. In recent years, new species have been added and genera reassigned. Shown above is one, Apareiodon affinis of southern Brazil, northern Argentina and Paraguay, which grows to 14cm long. It looks similar to several Asian fish including the Siamese Algae-eater but with a tetra-like adipose fin and to some African characins line Nannocharax parvus. It props itself on its pectoral fins on the river/stream bed.

Another of those with the name Darter Characin also has a scientific name that is applied (rightly and wrongly) to several new and old members of its genus: Characidium fasciatum. It is/They are also called the Banded Darter Characin. The one shown is native to southern Brazil and the Rio Parana system and grows to 7cm long but many others look similar. It also sits propped up on its pectoral fins on a stream bed and waits for food to pass by on the current. Several African characins in the genus Nannocharax also look similar.