Trichomycterus is a genus of fish in the family Trichomycteridae, the largest genus of its family with over 170 species currently described. This genus is native to freshwater habitats in Central and South America. These fish are generally small, usually about 5 to 15 cm (2–6 in) in standard length, although the largest, T. rivulatus, can reach more than twice this size. Species differ from one another primarily in body proportions, fin ray counts and colouration. Despite their relatively small size, some, such as T. punctulatus, support fisheries and are important in the local cuisine.

Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes. This family includes the candiru fish, feared by some people for its alleged habit of entering into the urethra of humans. They are one of the few parasitic chordates. Another species is the life monsefuano which was important to the Moche culture and still an important part of Peruvian cuisine.