''Acanthicus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of large, South American suckermouth armored catfishes native to the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technology c ...

and

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

basins, and possibly in

Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...

. The name ''Acanthicus'' is derived from the Greek, ''akanthikos'' meaning thorny, spiny. Fish of this genus are known as lyre-tail plecos. These species are found in large rivers, primarily in areas with a rocky bottom and a moderate or strong current.

Species

There are currently 2 recognized species in this genus: * '' Acanthicus adonis'' Isbrücker & Nijssen, 1988 (adonis pleco, polka dot lyre-tail pleco) * '' Acanthicus hystrix''

Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he rec ...

''in''

Spix Johann Baptist Ritter von Spix (9 February 1781 – 13 March 1826) was a German biologist. From his expedition to Brazil, he brought to Germany a large variety of specimens of plants, insects, mammals, birds, amphibians and fish. They constitute ...

& Agassiz, 1829 (lyre-tail pleco) ''A. hystrix'' is also known as L155 by the

L-number The L-number system is a semi-scientific classification system of catfish based on photographs of shipments of tropical catfish of the family Loricariidae published by the German aquarium magazine DATZ (Die Aquarien- und Terrarienzeitschrift (The ...

system. Possibly undescribed species in the genus are L193 (

basin) and L407 ( Branco basin), but these may be variants of ''A. hystrix''.

Description

''Acanthicus'' are among the largest species in the family Loricariidae. The largest officially measured ''A. adonis'' is in

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

(SL), and the largest officially measured ''A. hystrix'' is SL, but both appear to reach about SL. These fish are relatively slender, spiny Loricariids that lack an adipose fin. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

possesses long filamentous lobes on the upper and lower margins and is forked. The

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

spines are extremely long. The entire dorsal surface of the head is covered in stout, sharp odontodes. The odontodes form a sharp keel on the lateral plates and, in juveniles, there are few to no odontodes on the plates above and below the keel rows. The cheek odontodes are fairly thin, but numerous. Males may have more and longer cheek odontodes and greatly elongated odontodes on the pectoral fin spine. The colour of these fish is black, dark gray or medium to dark brown. Unlike ''A. hystrix'', juvenile ''A. adonis'' shows white spots; these are reduced with age and large adults may lack them.

In the aquarium

Both ''A. adonis'' and ''A. hystrix'' are sometimes kept in aquariums, and especially the densely white-spotted juveniles of the former species are regularly seen in the trade. They are opportunistic, omnivorous feeders that require well-oxygenated water. Their massive adult size and territorially aggressive behavior means that a very large tank is required. The territorial behavior is mostly aimed at other suckermouth armored catfishes and during disputes ''Acanthicus'' have even been known to kill ''

Pterygoplichthys gibbiceps ''Pterygoplichthys gibbiceps'' is a species of armored catfish native to Brazil, Ecuador, Peru and Venezuela where it is found in the Orinoco and Amazon basins. ''Pterygoplichthys gibbiceps'' shows all the characteristic features of its genus� ...

'' (itself typically considered a robust species). They have been bred in captivity.

References

{{Taxonbar, from=Q2290544 Ancistrini Fish of South America Fish of the Amazon basin Fauna of Brazil Catfish genera Taxa named by Louis Agassiz Freshwater fish genera