{{Short description|Genus of fishes}} {{Automatic taxobox | image = Otocinclus arnoldi (1).JPG | image_caption = ''Otocinclus arnoldi'' | taxon = Otocinclus | authority = Cope, 1871<ref name = "Cof family">{{Cof family|family=Hypoptopomatinae|access-date=22 April 2026}}</ref> | type_species = ''Otocinclus vestitus'' | type_species_authority = Cope, 1872<ref name = "Cof family"/> | synonyms = {{Genus list | Macrotocinclus | Isbrücker & Seidel, 2001 }} | synonyms_ref = <ref name = "Cof family"/> }}
'''''Otocinclus''''' is a genus of freshwater ray-finned fish belonging to the family Loricariidae, the suckermouth armoured catfishes, and the subfamily Hypoptopomatinae, the cascudinhos. The catfishes in this genus are found in South America.<ref name = "Cof family"/> These catfishes are commonly known as "dwarf suckers" or "otos". This genus, like other loricariids, is characterized by rows of armour plating covering the body, as well as the underslung suckermouth. They are generally small in size; ''O. tapirape'' is the smallest of the species (2.4 cm), while ''O. flexilis'' is the biggest (5.5 cm).<ref name=FB/> These species have adaptations that allow them to breathe air. A duct forms at the junction between the esophagus and the stomach and expands into an enlarged, ring-like diverticulum, characteristic of this genus, which allows air-breathing.<ref name=Armbruster1998>Armbruster, J.W. (1998): [http://www.auburn.edu/academic/science_math/res_area/loricariid/fish_key/Air.pdf Modifications of the Digestive Tract for Holding Air in Loricariid and Scoloplacid Catfishes.] ''Copeia, 1998 (3): 663–675.''</ref> ''Otocinclus'' are popular aquarium fish, and they are often purchased as algae eaters. It is difficult to breed them in captivity, and mostly wild caught ''Otocinclus'' are available to hobbyists. This genus is widely distributed east of the Andes of South America, throughout the lowlands from northern Venezuela to northern Argentina, but are generally absent from the Amazon and the Orinoco lowlands.<ref name=Axenrot2003/>
==Etymology== The ''Otocinclus'' name is derived from the Greek ''oto'', meaning ear and the Latin ''cinclus'', meaning a latticework, an allusion to the holes in the head in the region of the ear.<ref name=FB>{{FishBase_genus | genus = Otocinclus | year = 2016 | month = June }}</ref>
==Taxonomy== ''Otocinclus'' is the most basal genus of the tribe Hypoptopomatini of the subfamily Hypoptopomatinae. However, phylogenetic relationships are currently under study and this genus may eventually be relocated.<ref name="Lehmann2006">Lehmann, A., P. (2006): [http://www.scielo.br/pdf/ni/v4n4/a01v4n4.pdf ''Otocinclus batmani'', a new species of hypoptopomatine catfish (Siluriformes: Loricariidae) from Colombia and Peru.] ''Neotropical Ichthyology, 4 (4): 379–383.''</ref> Its monophyly is supported by seven derived features. ''O. batmani'', ''O. bororo'', ''O cocama'', ''O. huaorani'', ''O. mariae'' and ''O. mura'' form a monophyletic group within this genus.<ref name=Lehmann2006/> A monophyletic group is also formed by ''O. flexilis'', ''O. mimulus'' and ''O. xakriaba'', which all share mimicry as a synapomorphy.<ref name=Axenrot2003/> ''Eschmeyer's Catalog of Fishes'' does not recognize tribes and so only places this genus in the Hypoptopomatinae.<ref name = ECoF>{{cite web |url=https://www.calacademy.org/scientists/catalog-of-fishes-classification/ |title=Eschmeyer's Catalog of Fishes Classification |editor1=Richard van der Laan |editor2=Ronald Fricke |access-date=21 December 2025 |work=Eschmeyer's Catalog of Fishes |publisher=California Academy of Sciences}}</ref>
==Species== ''Otocinclus'' contains the following valid species:<ref name = "Cof genus">{{Cof genus|genus=Otocinclus|access-date=22 April 2026}}</ref> {{Linked species list | Otocinclus affinis | Steindachner, 1877 | Otocinclus arnoldi | Regan, 1909 | Otocinclus batmani | Lehmann A., 2006 | Otocinclus bororo | Schaefer, 1997 | Otocinclus caxarari | Schaefer, 1997 | Otocinclus cocama | Reis, 2004 | Otocinclus flexilis | Cope, 1894 | Otocinclus hasemani | Steindachner, 1915 | Otocinclus hoppei | A. Miranda Ribeiro, 1939 | Otocinclus huaorani | Schaefer, 1997 | Otocinclus juruenae | Ribeiro & Lehmann A. 2016 | Otocinclus macrospilus | C.H. Eigenmann & W. R. Allen, 1942 | Otocinclus mariae | Fowler, 1940 | Otocinclus mimulus | Axenrot & S. O. Kullander, 2003 | Otocinclus mura | Schaefer, 1997 | Otocinclus tapirape | Britto & Moreira, 2002 | Otocinclus vestitus | Cope, 1872 | Otocinclus vittatus | Regan, 1904 | Otocinclus xakriaba | Schaefer, 1997 }}
==Ecology== Species of this genus are diurnal and generally are found in small streams or along the margins of larger rivers, clinging to substrates using their suckermouth. The fish of this genus primarily feed on algae or aufwuchs on roots, stones, macrophytes and broad-leaved grasses.<ref name=Axenrot2003/> They inhabit well-oxygenated, moderate- to slow-flowing environments, often near river banks. They are found near the surface of the water, but are often associated with vegetation or other structures.<ref name=Lehmann2006/> They lay adhesive eggs and do not guard them; this is in contrast to many other loricariids where the male builds a nest and guards the eggs.<ref name=Fenner>{{cite web | url = http://www.wetwebmedia.com/FWSubWebIndex/otocinclusart.htm | title = The Ideal Algae Eater? The Littlest South American Suckermouth Catfishes, Genus ''Otocinclus'' |author=Fenner, R. }}</ref> These fish live in shoals or schools.<ref name=Axenrot2003/> ''Otocinclus'' are able to breathe air. Prior to surfacing, they will release air through their gills and mouth. Upon returning to the bottom, the fish do not need to pump their buccal cavities, indicating they are absorbing oxygen from the swallowed air.<ref name=Armbruster1998/>
''O. flexilis'', ''O. mimulus'' and ''O. xakriaba'' are considered to be Batesian mimics of certain former Corydoras species (''H. paleatum'' (formerly ''C. paleatus''), ''H. diphyes'' (formerly ''C. diphyes'') and ''B. garbei'' (formerly ''C. garbei''), respectively). These species have bony plates of armor and strong spines as defenses, making them less palatable; by mimicking these species in size and coloration, ''Otocinclus'' spp. avoid predation.<ref name=Axenrot2003>Axenrot, T.E. & Kullander, S.O. (2003): [http://www.ecology.su.se/pdfs/axenrot/fish.pdf ''Corydoras diphyes'' (Siluriformes: Callichthyidae) and ''Otocinclus mimulus'' (Siluriformes: Loricariidae), two new species of catfishes from Paraguay, a case of mimetic association.] {{webarchive|url=https://web.archive.org/web/20090205144416/http://www.ecology.su.se/pdfs/axenrot/fish.pdf |date=2009-02-05 }} ''Ichthyological Exploration of Freshwaters, 14 (3): 249–272.''</ref>
==References== {{Reflist}}
{{Taxonbar|from=Q1141986}}
Category:Hypoptopomatinae Category:Otocinclus Category:Fish of South America Category:Catfish genera Category:Taxa named by Edward Drinker Cope Category:Freshwater fish genera