Loach

{{Short description|Suborder of ray-finned fish}} {{Other uses|Loach (disambiguation)}} {{Automatic taxobox | fossil_range = {{Fossil range|Oligocene|recent}}<ref>{{cite journal |last1=Chen |first1=Jiao |title=First fossil cobitid (Teleostei: Cypriniformes) from EarlyMiddle Oligocene deposits of South China |journal=Vertebrata PalAsiatica |date=2015 |url=http://www.ivpp.ac.cn/cbw/gjzdwxb/xbwzxz/201512/P020151204533862469713.pdf}}</ref> | name = Loaches | taxon = Cobitoidea | authority = Fitzinger, 1832<ref name = N&T>{{cite journal |author=Thomas J. Near |author2=Christine E. Thacker |title=Phylogenetic Classification of Living and Fossil Ray-Finned Fishes (Actinopterygii) |journal=Bulletin of the Peabody Museum of Natural History |volume=65 |issue=1 |pages=3–302 |doi=10.3374/014.065.0101}}</ref> | image = <imagemap> File:Loaches.jpg|250px

rect 0 0 624 416 Botiidae rect 644 0 1268 416 Cobitidae rect 0 436 624 852 Gastromyzontidae rect 644 436 1268 852 Nemacheilidae

</imagemap> | image_caption = Examples of several loach families | subdivision_ranks = Families | subdivision = see text }}

'''Loaches''' are ray-finned fishes of the suborder '''Cobitoidei'''. They are freshwater, benthic (bottom-dwelling) fish found in rivers and creeks throughout Eurasia and northern Africa.<ref name=":0">{{Cite journal|last=Kottelat|first=M.|date=2012|title=Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei)|journal=The Raffles Bulletin of Zoology|volume=Supplement no. 26|pages=1–199}}</ref> Loaches are among the most diverse groups of fish; the 1249 known species of Cobitoidei make up about 107 genera divided among 9 families.<ref>{{Cite web|url=http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp|title=Eschmeyer's catalog of fishes: genera, species, references|date=2019|editor-last=Fricke|editor-first=R.|editor2-last=Eschmeyer|editor2-first=W. N.|id=Electronic version accessed February 2019.|editor3-last=van der Laan|editor3-first=R.}}</ref><ref>{{Cite book|title=Fishes of the World|last1=Nelson|first1=J. S.|last2=Grande|first2=T. C.|last3=Wilson|first3=M. V. H.|publisher=John Wiley & Sons|year=2016|isbn=978-1-118-34233-6|edition=5th|location=Hoboken, New Jersey|pages=189–193}}</ref>

== Etymology == The name Cobitoidei comes from the type genus, ''Cobitis'', described by Carl Linnaeus in his landmark 1758 10th edition of ''Systema Naturae''. However, its origin predates modern zoological nomenclature and derives from a term used by Aristotle to refer to "small fishes that bury... like the gudgeon."<ref name=":0" />

== Description == left|thumb|Common horseface loach ''Acantopsis rungthipae''|alt=

Loaches display a wide variety of morphologies, making the group difficult to characterize as a whole using external traits. They range in adult length from the 23 mm (1 in) miniature eel-loach, ''Pangio longimanus'', to the 50 cm (20 in) imperial flower loach, ''Leptobotia elongata'', with the latter weighing up to 3 kg (6.6 lbs).<ref>{{Cite journal|last1=Britz|first1=R.|last2=Kottelat|first2=M.|date=2009|title=''Pangio longimanus'', a miniature species of eel-loach from Central Laos (Teleostei: Cypriniformes: Cobitidae)|journal=Ichthyological Exploration of Freshwaters|volume=20|issue=4|pages=371–376|issn=0936-9902}}</ref><ref>{{Cite journal|last1=Li|first1=L.|last2=Wei Wei|first2=Q.|last3=Ming Wu|first3=J.|last4=Zhang|first4=H.|last5=Liu|first5=Y.|last6=Xie|first6=X.|date=2015|title=Diet of ''Leptobotia elongata'' revealed by stomach content analysis and inferred from stable isotope signatures|url=http://ir.igsnrr.ac.cn/handle/311030/38701|journal=Environmental Biology of Fishes|volume=98|issue=8|pages=1965–1978|doi=10.1007/s10641-015-0414-4|s2cid=18612635|doi-access=free}}</ref><ref>{{Cite book|title=The Freshwater Fishes of China—Central Asiatic Expeditions|last=Nichols|first=J. T.|date=1943|publisher=American Museum of Natural History|location=New York|page=203}}</ref> Most loaches are small, narrow-bodied and elongate, with minute cycloid scales that are often embedded under the skin, patterns of brown-to-black pigment along the dorsal surface and sides, and three or more pairs of whisker-like barbels at the mouth.<ref name=":1">{{Cite journal|last=Conway|first=K. W.|date=2011|title=Osteology of the South Asian genus ''Psilorhynchus'' McClelland, 1839 (Teleostei: Ostariophysi: Psilorhynchidae), with investigation of its phylogenetic relationships within the order Cypriniformes|journal=Zoological Journal of the Linnean Society|volume=163|pages=50–154|doi=10.1111/j.1096-3642.2011.00698.x|doi-access=free}}</ref> The type species of the family Cobitidae, ''Cobitis taenia'', has a body shape and pigment pattern typical of Cobitoidei. However, many loaches are eel-like or conversely, quite stout-bodied; some balitorids have large, visible scales.<ref>{{Cite journal|last=Kottelat|first=M.|date=1988|title=Indian and Indochinese species of ''Balitora'' (Osteichthyes: Cypriniformes) with descriptions of two new species and comments on the family-group names Balitoridae and Homalopteridae|journal=Revue suisse de Zoologie|volume=95|issue=2|pages=487–504|doi=10.5962/bhl.part.79667|doi-access=free}}</ref>

Loaches in the families Cobitidae, Botiidae, and Serpenticobitidae possess a bifid, protrusible spine below the eye, or in the case of the genus ''Acantopsis'', between the eye and the tip of the snout.<ref name=":2">{{Cite journal|last1=Bohlen|first1=J.|last2=Šlechtová|first2=V.|last3=Šlechta|first3=V.|last4=Šlechtová|first4=V.|last5=Sember|first5=A.|last6=Ráb|first6=P.|date=2016|title=A ploidy difference represents an impassable barrier for hybridisation in animals. Is there an exception among botiid loaches (Teleostei: Botiidae)?|journal=PLOS ONE|volume=11|issue=7|article-number=e0159311|doi=10.1371/journal.pone.0159311|pmid=27442252|pmc=4956246|bibcode=2016PLoSO..1159311B|doi-access=free}}</ref><ref>{{Cite journal|last1=Boyd|first1=D. A.|last2=Nithirojpakdee|first2=P.|last3=Deein|first3=G.|last4=Vidthayanon|first4=C.|last5=Grudpan|first5=C.|last6=Tangjitjaroen|first6=W.|last7=Pfeiffer|first7=J. M.|last8=Randall|first8=Z. S.|last9=Srisombat|first9=T.|date=2017|title=Revision of the horseface loaches (Cobitidae, ''Acantopsis''), with descriptions of three new species from Southeast Asia|journal=Zootaxa|volume=4341|issue=2|pages=151–192|last10=Page|first10=L. M.|doi=10.11646/zootaxa.4341.2.1|pmid=29245684|doi-access=free}}</ref>

== Taxonomy == thumb|''Cobitis'' species described by Linnaeus|alt=|300x300px

=== Classification === Cobitoidei is a suborder within the order Cypriniformes, one of the most diverse groups of vertebrates. The order is commonly known as "minnows, carps, loaches, and relatives," and has included the suckers (Catostomidae) and algae eaters (Gyrinocheilidae), these are now regarded as separate suborders, the Gyrinocheiloidei and the Catostomoidei.<ref name = ECoF>{{cite web |url=https://www.calacademy.org/scientists/catalog-of-fishes-classification |title=Eschmeyer's Catalog of Fishes Classification |access-date=26 November 2024 |publisher=California Academy of Sciences}}</ref> Members of the latter family, which contains only a single genus ''Gyrinocheilus'', are sometimes referred to as sucking loaches. It is uncertain if Gyrinocheilidae, or a clade containing both Gyrinocheilidae and Catostomidae, is sister to Cobitoidei.<ref name=":3" />

''Eschmeyer's Catalog of Fishes'' classifies the families in the suborder as follows:<ref name = ECoF/> * Suborder Cobitoidei Fitzinger, 1832 ** Family Botiidae Berg, 1940 (pointface loaches) ** Family Vaillantellidae Nalbant & Bănărescu, 1977 (longfin loaches) ** Family Cobitidae Swainson, 1838 (spined loaches) ** Family Barbuccidae Kottelat, 2012 (scooter loaches) ** Family Gastromyzontidae Fowler, 1905 (hillstream loaches) ** Family Serpenticobitidae Kottelat, 2012 (snake loaches) ** Family Balitoridae Swainson, 1839 (river loaches) ** Family Ellopostomatidae Bohlen & Šlechtová, 2009 (square-head loaches) ** Family Nemacheilidae Regan, 1911 (brook loaches)

==== History of classification ==== At the turn of the 20th century only two families of loaches had been described, and of these only Cobitidae was widely recognized by taxonomists. In the early 1900s, the American ichthyologist Fowler and the Indian ichthyologist Hora recognized what would come to be known as Balitoridae and Gastromyzontidae.<ref>{{Cite journal|last=Fowler|first=H. W.|date=1905|title=Some Fishes from Borneo|journal=Proceedings of the Academy of Natural Sciences of Philadelphia|volume=57|pages=455–523|jstor=4063033}}</ref><ref>{{Cite journal|last=Hora|first=S. L.|date=1932|title=Classification, bionomics and evolution of homalopterid fishes|journal=Memoirs of the Indian Museum|volume=12|issue=2|pages=263–330}}</ref> Nemachelidae, and later Botiidae, were described as subfamilies of Cobitidae until their elevation to family status in 2002.<ref>{{Cite journal|last1=Liu|first1=H.|last2=Tzeng|first2=C. S.|last3=Teng|first3=H. Y.|date=2002|title=Sequence variations in the mitochondrial DNA control region and their implications for the phylogeny of the Cypriniformes|url=http://ir.ihb.ac.cn/handle/152342/9868|journal=Canadian Journal of Zoology|volume=80|issue=3|pages=569–581|doi=10.1139/z02-035|url-access=subscription}}</ref><ref>{{Cite journal|last1=Tang|first1=Q.|last2=Liu|first2=H.|last3=Mayden|first3=R.|last4=Xiong|first4=B.|date=2006|title=Comparison of evolutionary rates in the mitochondrial DNA cytochrome b gene and control region and their implications for phylogeny of the Cobitoidea (Teleostei: Cypriniformes)|url=http://ir.ihb.ac.cn/handle/152342/8986|journal=Molecular Phylogenetics and Evolution|volume=39|issue=2|pages=347–357|doi=10.1016/j.ympev.2005.08.007|pmid=16213167|url-access=subscription}}</ref><ref>{{Cite journal|last1=Liu|first1=S.|last2=Mayden|first2=R.|last3=Zhang|first3=J.|last4=Yu|first4=D.|last5=Tang|first5=Q.|last6=Deng|first6=X.|last7=Liu|first7=H.|date=2012|title=Phylogenetic relationships of the Cobitoidea (Teleostei: Cypriniformes) inferred from mitochondrial and nuclear genes with analyses of gene evolution|url=http://ir.ihb.ac.cn/handle/342005/17156|journal=Gene|volume=508|issue=1|pages=60–72|doi=10.1016/j.gene.2012.07.040|pmid=22868207|url-access=subscription}}</ref> Owing to shared morphological characteristics (see osteology, below) the relationship of the botiid and cobitid loaches was particularly difficult to resolve until the advent of molecular phylogenetics. Three of the nine families, containing only two or three species apiece, were recognized within the last ten years.<ref name=":3">{{Cite journal|last1=Armbruster|first1=J. W.|last2=Tan|first2=M.|date=2018|title=Phylogenetic classification of extant genera of fishes of the order Cypriniformes (Teleostei: Ostariophysi)|journal=Zootaxa|volume=4476|issue=1|pages=6–39|doi=10.11646/zootaxa.4476.1.4|pmid=30313339|doi-access=free}}</ref>

=== Phylogeny === Reproduction of molecular phylogeny of Cobitoidea from Bohlen & Šlechtová, 2009,<ref>{{Cite journal|last1=Bohlen|first1=J.|last2=Šlechtová|first2=V.|date=2009|title=Phylogenetic position of the fish genus ''Ellopostoma'' (Teleostei: Cypriniformes) using molecular genetic data|journal=Ichthyological Exploration of Freshwaters|volume=20|issue=2|pages=157–162|issn=0936-9902}}</ref> with common names following Eschmeyer's Catalog of Fishes.<ref>{{Cite web|url=http://www.calacademy.org/scientists/catalog-of-fishes-classification/|title=Eschmeyer's catalog of fishes: classification|date=2019|editor-last=Van der Laan|editor-first=R.|editor2-last=Fricke|editor2-first=R.|id=Electronic version accessed February 2019.|editor3-last=Eschmeyer|editor3-first=W. N.}}</ref>thumb|Serpent loach ''Serpenticobitis cingulata''|alt=|300x300px{{Clade|{{clade |1=Gyrinocheilidae Gill 1905 '''algae eaters''' |label2=Cobitoidea |2={{clade |1=Botiidae Berg 1940 '''pointface loaches''' |2={{clade |1=Vaillantellidae Nalbant & Bănărescu 1977 '''longfin loaches''' |2={{clade |1=Cobitidae Swainson 1838 '''true''' or '''spined loaches''' |2={{clade |1=Ellopostomatidae Bohlen & Šlechtová 2009 '''squarehead loaches''' |2=Nemacheilidae Regan 1911 '''brook loaches''' |3={{clade |1=Barbuccidae Kottelat 2012 '''scooter loaches''' |2={{clade |1=Balitoridae Swainson 1839 '''river loaches''' |2={{clade |1=Serpenticobitidae Kottelat 2012 '''serpent loaches''' |2=Gastromyzontidae Fowler 1905 '''hillstream loaches''' }} }} }} }} }} }} }} }}|style=font-size:100%}}

=== Osteology === Among loaches, the majority of known morphological synapomorphies (shared characters derived from a common ancestor) are osteological. In particular, modifications to the ethmoid and surrounding bones within the neurocranium unite Cobitoidei, in addition to certain lateral-line canal ossifications.<ref name=":1" /> An erectile suborbital spine, a modification of the lateral ethmoid, was formerly thought to represent a synapomorphy between Cobitidae and Botiidae.<ref>{{Cite journal|last=Sawada|first=Y.|date=1982|title=Phylogeny and zoogeography of the superfamily Cobitoidea (Cyprinoidei, Cypriniformes)|journal=Memoirs of the Faculty of Fisheries Sciences, Hokkaido University|volume=28|issue=2|pages=65–223}}</ref> It is now considered a pleisiomorphy of Cobitoidei, a character shared by the common ancestor but lost in most loach lineages.<ref>{{Cite journal|last1=Šlechtová|first1=V.|last2=Bohlen|first2=J.|last3=Tan|first3=H. H.|date=2007|title=Families of Cobitoidea (Teleostei; Cypriniformes) as revealed from nuclear genetic data and the position of the mysterious genera ''Barbucca'', ''Psilorhynchus'', ''Serpenticobitis'' and ''Vaillantella''|journal=Molecular Phylogenetics and Evolution|volume=44|issue=3|pages=1358–1365|doi=10.1016/j.ympev.2007.02.019|pmid=17433724}}</ref> The suborbital spine is also retained in the serpent loaches, Serpenticobitidae.<ref name=":2" />

== Habitat and distribution == Loaches are found in a wide variety of habitats throughout Europe, northern Africa, and central and Southeast Asia. Most families occur predominantly in rocky mountain streams at high elevations, but almost all have lowland representatives as well.<ref name=":0" /> Many species of Cobitidae burrow in the sand and inhabit riverbeds in broad, flat terrain. At least three families contain blind, troglomorphic species adapted to life in caves.

== Relationship with humans == thumb|The oriental weatherfish or pond loach is widely introduced outside its native range Some loaches are important food fish, especially in East and Southeast Asia where they are a common sight in markets.

Loaches are popular in the aquarium trade. Loaches are fed sinking discs designed for them in the aquarium. Some of the most well-known examples are the clown loach (''Chromobotia macracanthus''), the kuhli loach (''Pangio kuhlii''), and the dwarf chain loach (''Ambastaia sidthimunki''). Botiid and gastromyzontid loaches also occasionally make their way into the trade.<ref>{{Cite book|title=Loaches: natural history and aquarium care|date=2008|publisher=T.F.H. Publications|isbn=978-0-7938-0620-1|location=Neptune City, NJ}}</ref>

Although loaches have a strictly Old World native distribution, the oriental weatherfish, ''Misgurnus anguillicaudatus'', (also known as the dojo loach) has been introduced in parts of the United States.<ref>{{Cite book|title=Nonindigenous fishes introduced into inland waters of the United States.|last1=Fuller|first1=P. L.|last2=Nico|first2=L. G.|last3=Williams|first3=J. D.|publisher=American Fisheries Society, Special Publication #27|year=1999|location=Bethesda, MD|page=176}}</ref><ref>{{Cite book|title=Fishes in the fresh waters of Florida: an identification guide and atlas|last1=Robins|first1=R. H.|last2=Page|first2=L. M.|last3=Williams|first3=J. D.|last4=Randall|first4=Z. S.|last5=Sheehy|first5=G. E.|publisher=University of Florida Press|year=2018|isbn=978-1-68340-033-2|location=Gainesville, Florida|pages=141–142}}</ref>

== References == {{Reflist}}

Category:Cobitoidei