Ancistrus

Species of the genus Ancistrus are fairly characteristic Loricariidae, with a body of generally diamond-shaped form, and a large head, particularly in the species Ancistrus ranunculus. Like all Loricariidae, their mouth is equipped with a large sucker, which allows them to adhere to the substrate. Their sizes vary from 12 to 15 cm on average, with maxima observed up to 18 cm for some old males. These species generally present fairly characteristic sexual dimorphism: the growths on the head of adult males are very developed, and branched. They are distributed around the mouth, and along a line on the forehead. In most species, females also carry similar growths, but distinctly less developed. They are never branched, and are present only around the mouth. They are absent from the forehead. These characteristic fleshy growths give it a bristly, brush-like appearance, hence their English common name of Bristlenose (literally "brush-nosed").

Species of the genus Ancistrus feed on the algae carpet that covers the substrate (roots, rocks), as well as the small creatures that live there (insect larvae, microorganisms…). They obtain their food from the environment by means of their oral sucker, by scraping the substrate. Unlike species of the genus Panaque, they do not possess the appropriate teeth, nor the commensal flora, which would allow them to digest the lignin of the wood, and therefore do not consume it. Despite the common misconception, the presence of roots in the tank is therefore not at all necessary for the survival of these species. In aquariums, they accept a wide range of foods, vegetables and fruits (zucchini, cucumber, apple…), bloodworms, or commercial dry foods (tablets and pellets).