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 known as bushynose or bristlenose catfish. Sometimes, they are called bushynose or bristlenose plecos instead, but this may lead to confusion as 'pleco' usually is used for Hypostomus plecostomus and a few of its close relatives but is also classed and or sold as a pleco by most places. The type species is Ancistrus cirrhosus. This genus is the largest genus within the tribe Ancistrini. The name ancistrus derives from the Ancient Greek agkistron 'hook' – a reference to the form of the cheek odontodes. The genera Pristiancistrus, Thysanocara and Xenocara are now synonyms of Ancistrus. Ancistrus species show all the typical features of the Loricariidae. This includes a body covered in bony plates and a ventral suckermouth. The feature most commonly associated with the genus are the fleshy tentacles found on the head in adult males; females may possess tentacles along the snout margin but they are smaller and they lack tentacles on the head. Tentacules, tentacles directly associated with odontodes, develop on the pectoral fin spine of the males of some species. Males also have evertible cheek odontodes which are less developed or absent in females. They also lack odontodes along the snout. In comparison with a typical loricariid (pleco), a bristlenose is typically shorter (4–6 inches or 15 cm or less), more flattened and fatter with a comparatively wider head. Colouration is typically mottled brown, grey or black. Small white or yellow spots are common. Unlike other loricariids which commonly grow to over a foot long, the bristlenose pleco may only grow to half the size, this makes it a suitable species for the smaller tank. Ancistrus species are unusual among vertebrates in possessing an X0 sex-determination system, which is dominant in many lineages of arthropod but very rare elsewhere in the animal kingdom. Ancistrus is one of the widest ranging genera of the family, and representatives are found throughout the range of Loricariidae. 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 two species, A. centrolepis and A. chagresi in Panama. Three species are true troglobites: A. cryptophthalmus, A. galani and A. formoso. These are the only known loricariids showing adaptions for a subterranean lifestyle with reduced pigmentation (appearing overall whitish) and eyes. There are currently 76 recognized species in this genus: The diet of this genus is typical for a Loricariid – algae and aufwuchs. Bristlenoses do not school but hide when not feeding, juveniles however are typically found in brightly lit shallows at the water margin making them susceptible to predation by birds.