''Panaqolus nocturnus'', known as the dusky panaque, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of small

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Loricariidae The Loricariidae is the largest family of catfish (order Siluriformes), with 92 genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are not ...

found in the Santiago and

Pastaza River The Pastaza River ( es, Río Pastaza, formerly known as the SumataraEnock, Charles Reginald (1914) ''Ecuador: its ancient and modern history, topography and natural resources, industries and social development'' Charles Scribner's sons, New York ...

basins in the upper Napo drainage in tropical

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. This species reaches a maximum standard length of .Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.

References

Ancistrini Catfish of South America Fish of Brazil Endemic fauna of Brazil Taxa named by Scott Allen Schaefer Taxa named by Donald J. Stewart Fish described in 1993 {{Loricariidae-stub