Archolaemus is a genus of South American glass knifefishes, family Sternopygidae.

[1][2][3] They occur in fast-flowing sections of rivers, including rapids, in the Amazon, Tocantins, São Francisco and Araguari basins.

[2] Depending on the exact species, they reach up to about 20–50 cm (8–20 in) in total length.

[3] During the day they hide in rocky crevices, but during the night they are active and feed on small invertebrates such as aquatic insect larvae.

[2] There are currently six recognized species in this genus:[2][3]