Ancistrus

Ancistrus is a genus of nocturnal freshwater fish in the family Loricariidae of order Siluriformes, native to freshwater habitats in South America and Panama. Fish of this genus are common in the aquarium trade where they are known as bushynose or bristlenose catfish. In the aquarium hobby they are often referred to as bushynose or bristlenose plecos instead, but this may lead to confusion as "pleco" usually is used for Hypostomus plecostomus and its allies and is often used as a catchall term for any loricariids remotely resembling that species.

Ancistrus is one of the widest ranging Loricariid genera, and representatives are found in most areas where the family in general is present. Many species are found in the rivers and floodplain areas of the Amazon basin, but there are also species elsewhere in tropical South America, as well as species on the island of Trinidad and two species, A. centrolepis and A. chagresi in Panama. Three species are true cavefish (troglobites): A. cryptophthalmus, A. galani and A. formoso. These are the only known loricariids that possess adaptions for a subterranean lifestyle, such as reduced pigmentation (appearing overall whitish) and eyes.