''Guyanancistrus tenuis'' is a species of catfish in the family Loricariidae. It is native to South America, where it occurs in a forested tributary of the

Mapaoni River Mapaoni River is a river of Amapá state in Brazil. It is a tributary of the Jari River, which is part of the Amazon River The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume ...

in the upper

Jari River The Jari River, or Jary River ( pt, Rio Jari), is a northern tributary of the Amazon River on the border between the states of Pará and Amapá in northeastern Brazil. It is in the most downstream regions of the Amazon Basin and borders the Gui ...

basin in French Guiana, near the Mitaraka Massif, which is a prominent massif in the area. The environment in which the species is typically found is a shallow mountain creek with medium to strong currents, a depth of 20 to 60 cm (7.9 to 23.6 inches), and some pools. The species reaches 9.1 cm (3.6 inches) in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

. Its specific epithet, ''tenuis'', is derived from Latin and refers to its slender body.

References

{{Taxonbar, from=Q47461415 Fish described in 2018 Freshwater fish of South America Hypostominae