leucos

Leucos is a genus in the family Cyprinidae, a large group of freshwater fishes that includes carps and minnows. The name Leucos is derived from the Greek leukos, meaning white, a reference to pale coloration observed in some species, and the genus has been placed within the subfamily Leuciscinae by several authorities.

In different taxonomic treatments, Leucos has been circumscribed differently. Some classifications include a small number of European river fishes that were previously placed in Leuciscus; others transfer these species to Leuciscus, Squalius, or related genera as morphological and genetic evidence has clarified relationships among European cyprinids. There is no universally accepted set of species assigned to Leucos, and the genus name may be treated as valid, a synonym, or a historical designation depending on the source.

Species placed in Leucos are native to Europe and adjacent regions. They inhabit freshwater habitats such as rivers and streams, often favoring moderate currents and clear waters. Like many cyprinids, they are generally omnivorous, feeding on detritus, invertebrates, and plant matter, and they tend to reach small to moderate sizes.