Pond loach

{{Short description|Species of freshwater fish}} {{More citations needed|date=February 2021}} {{Speciesbox | image = Misgurnus anguillicaudatus.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Zhao, H. |date=2012 |title=''Misgurnus anguillicaudatus'' |volume=2012 |article-number=e.T166158A1115635 |doi=10.2305/IUCN.UK.2012-1.RLTS.T166158A1115635.en |access-date=19 November 2021}}</ref> | taxon = Misgurnus anguillicaudatus | authority = (Cantor, 1842) | synonyms = * ''Cobitis anguillicaudata'' Cantor, 1842 * ''Misgurnus lividus'' (Sauvage & Dabry de Thiersant, 1874) * ''Nemacheilus lividus'' Sauvage & Dabry de Thiersant, 1874 * ''Misgurnus crossochilus'' Sauvage, 1878 * ''Ussuria leptocephala'' Nikolskii, 1903 * ''Misgurnus punctatus'' Oshima, 1926 * ''Misgurnus elongatus'' Kimura, 1934 }}

The '''pond loach''' ('''''Misgurnus anguillicaudatus'''''), also known as the '''Dojo loach''',<ref name="Pete">{{Cite web |last=Pete|first=Andrew |date=8 October 2021|title=Dojo Loach Care: Tank Mates, Tank Size, Feeding And More |url=https://fishkeepingproject.com/dojo-loach-care/ |access-date=28 November 2022 |website=Fishkeeping Project |language=en-US |url-status=usurped |archive-url=https://web.archive.org/web/20220405155240/https://fishkeepingproject.com/dojo-loach-care/ |archive-date=5 April 2022}}</ref>{{Self-published inline|date=April 2024}} '''oriental weatherloach'''<ref name=fishesofaustralia>Gomon, M.F. & Bray, D.J. (2020). [https://fishesofaustralia.net.au/home/species/4333 Oriental Weatherloach, ''Misgurnus anguillicaudatus'' (Cantor 1842)], ''Fishes of Australia'', Museums Victoria. Retrieved 2 February 2023.</ref> or '''oriental weatherfish''',<ref name="Belcik">{{Cite thesis|last=Belcik|first=John|year=2017|title=Population Genetics and Distribution of the Oriental Weatherfish, ''Misgurnus anguillicaudatus'', in Chicago Area Waterways|url=https://ecommons.luc.edu/luc_theses/3556|type=Master of Science|institution=Loyola University Chicago|access-date=28 November 2022}}</ref> is a freshwater fish in the loach family Cobitidae. They are native to East Asia, but are also popular as an aquarium fish and introduced elsewhere in Asia and to Europe, America and Australia.<ref name="iucn status 19 November 2021" /><ref>{{cite news|url=http://trove.nla.gov.au/newspaper/article/118193542|first=Bruce|last=Juddery|author-link=Bruce Juddery|date=26 July 1994|page=10|newspaper=The Canberra Times|title=Tough Asian fish a great survivor|access-date=28 November 2022|via=Trove}}</ref> The alternate name '''weather loach''' is shared with several other Cobitidae, including the other members of the genus ''Misgurnus'' and the spotted weather loach (''Cobitis taenia'', commonly known as spined loach). This term comes from their ability to detect changes in barometric pressure before a storm and react with frantic swimming or standing on end.

==Description== Wild pond loaches can grow up to {{cvt|12|in|cm}} long, but may only reach a length of {{cvt|6|in|cm}} in captivity.<ref name="Pete"/>{{Self-published inline|date=April 2024}} They also come in a variety of colors, such as pink, orange, albino and gray, and can vary in colour from yellow to olive green, to a common light brown or grey with lighter undersides. Like many other loaches, pond loaches have slender, eel-like body. The mouth of the loach is surrounded by three sets of barbels, which are used to sift through silt or pebbles to find food, and also to dig under gravel and sand to conceal the fish out of nervousness or self-defence, unlike the other loaches who use the spines beneath the eyes.

Pond loaches are bottom-dwelling omnivores, feeding mainly on algae or scavenging organic materials, and may also eat on tubifex worms and other small aquatic invertebrates.

Pond loaches are very hardy fish that can live in poor-quality water, and can survive short periods of drought by producing a layer of moisture-trapping mucus to keep themselves damp. Despite their resiliance against water conditions, pond loaches should still be kept in pristine water to ensure their health and prosperity within the home aquarium or pond. These loaches prefer a soft, sandy, smooth stone, fine gravel substrate, or bare bottomed tank as opposed to any form of rocks or rough gravel, which have been known to damage the sensitive barbels and skin.<ref>{{Cite web |title=Misgurnus anguillicaudatus – Oriental Weather Loach — Seriously Fish |url=https://www.seriouslyfish.com/species/misgurnus-anguillicaudatus/ |access-date=2023-02-24}}</ref>

== Physiology == Unlike most other fishes, the pond loach can burrow into and hide in soft substrates, breathe atmospheric air through enteral respiration if necessary, and survive for long periods of time outside of the water.<ref name="Belcik"/><ref name=":0" /> For the pond loach to survive on land for extended periods of time, it has physiological adaptations to reduce toxic ammonia concentrations in the body and maintain homeostasis and normal functioning of tissues. When on land, the pond loach can suppress protein breakdown and catabolism (which avoids creating ammonia), switch to partial amino catabolism (which creates non-toxic alanine instead of ammonia), convert ammonia to non-toxic glutamine, and get rid of ammonia by excreting it as NH3 gas.<ref name=":0">{{Cite journal|last1=Ip|first1=Y. K.|last2=Chew|first2=S. F.|last3=Randall|first3=D. J.|date=September 2004|title=Five Tropical Air-Breathing Fishes, Six Different Strategies to Defend against Ammonia Toxicity on Land|journal=Physiological and Biochemical Zoology|volume=77|issue=5|pages=768–782|doi=10.1086/422057|pmid=15547795|s2cid=20545085|issn=1522-2152}}</ref><ref>{{Cite journal|last1=Chew|first1=Shit F.|last2=Jin|first2=Yi|last3=Ip|first3=Yuen K.|date=March 2001|title=The Loach ''Misgurnus anguillicaudatus'' Reduces Amino Acid Catabolism and Accumulates Alanine and Glutamine during Aerial Exposure|journal=Physiological and Biochemical Zoology|volume=74|issue=2|pages=226–237|doi=10.1086/319663|pmid=11247742|s2cid=23099421|issn=1522-2152}}</ref> The pond loach is also relatively insensitive to ammonia, though it is not known how pond loach tissues, especially the heart and brain, are able to function at ammonia concentrations that would be lethal for other species. One hypothesis is that the pond loach may maintain normal brain cell functioning by altering the sensitivity and specificity of receptors in the brain for potassium ions, which otherwise would be overwhelmed by ammonia.<ref name=":0" />

==Clonal reproduction==

The pond loach can reproduce sexually and asexually. Although sexually reproducing diploids (2n = 50) are most common in Japan, asexual clones also occur in a few wild populations.<ref>Yoshikawa H, Morishima K, Fujimoto T, Saito T, Kobayashi T, Yamaha E, Arai K. Chromosome doubling in early spermatogonia produces diploid spermatozoa in a natural clonal fish. Biol Reprod. 2009 May;80(5):973-9. doi: 10.1095/biolreprod.108.075150. Epub 2009 Jan 14. PMID 19144955</ref> Clonally reproducing diploid loaches produce unreduced diploid eggs that develop into identical clones (without any genetic contribution from sperm) by the process of gynogenesis.<ref name = Itono2006>Itono M, Morishima K, Fujimoto T, Bando E, Yamaha E, Arai K. Premeiotic endomitosis produces diploid eggs in the natural clone loach, Misgurnus anguillicaudatus (Teleostei: Cobitidae). J Exp Zool A Comp Exp Biol. 2006 Jun 1;305(6):513-23. doi: 10.1002/jez.a.283. PMID 16526047</ref> During gynogenesis, an egg is activated by a sperm that degenerates without fusing with the egg nucleus, so that the resulting embryo contains only maternal chromosomes. This asexual process involves the duplication of chromosomes by mitosis without cytokinesis prior to meiosis, i.e. premeiotic endomitosis, followed by a quasi-normal meiosis to produce diploid eggs.<ref name = Itono2006/>

==In the aquarium== right||frameless|alt=Side view of a pink loach right|frameless|alt=Orange specimen right|frameless|alt=Macro photograph

Pond loaches are quite active, athletic swimmers, with their activity levels, allegedly, being influenced by oncoming storms or changes in barometric pressure (hence the name "weather" loach). They are generally active throughout the day, only resting intermittently, but become notably crepuscular and nocturnal as the day progresses, foraging and swimming more actively in the hours between sunset and sunrise. For this reason, many aquarists and keepers will adjust their fishes' communal feeding time to be in the evening, an important point to consider if cohabitating pond loaches with other species. When not resting out-of-sight, pond loaches can often be seen lying on the surfaces of larger-leaved plants (such as ''Anubias'', ''Echinodorus'' or ''Nymphaea'' sp.), on driftwood, or on smooth rocks, and often in comedic or ridiculous positions. They may even appear lifeless, lying on their sides or back, before suddenly springing back to "life" and continuing with their routine behavior. This "playing-dead" style of rest is also well known from other related species, like the clown loach (''Chromobotia macracanthus'').

The pond loach is an exceptionally peaceful, hardy species, capable of withstanding unheated aquariums, and preferring to live in outdoor ponds. Not being a tropical species by nature, water temperatures above {{convert|70|to|75|F|C}} are not recommended for, and can cause respiratory issues, fatigue, and even death, in pond loaches. For this reason they make a viable companion species for goldfish, which also are a cold-water species. They show virtually no aggression or hostility to any other tankmates, including their own kind, mostly minding their own business despite being a highly sociable species; if housing multiple individuals, which is usually recommended, pond loaches will often "cuddle" and rest huddled-together. The species is widely sold at pet stores and local fish shops. Given their somewhat "goofy" and cantankerous nature, they are not particularly aloof or shy, and thus can develop a "friendliness" towards their caretakers, swimming around their owner's hands and arms, allowing for physical contact and even hand-feeding.

The larger a pond loach matures, the more muscular and likely to breach the water's surface they become; due to their jumping prowess, the average aquarium cover should be secured with tape or additional sheets of acrylic or plastic, or panes of additional glass. If kept outside, proper netting over the water feature may be required. If a pond loach successfully jumps from the water (and is not subsequently caught by a bird or other animal), it may crawl on the ground for some time, breathing atmospheric oxygen, before eventually suffocating. Despite their ability to move terrestrially between shallow bodies of water in the wild, something many species do (like killifish), they do not have the same respiratory adaptations as, for example, the lungfishes or mudskippers. Also, in an indoor aquarium setting, care must be taken to cover any tubing or pipes that are large enough for a loach to fit inside of, as they may even travel up filtration tubes and become stuck in the filter itself. Pond loaches enjoy digging and burrowing themselves in the substrate of their tank, so make sure that your substrate is fine enough for them to dig in. If you keep live plants in your tank, they will be uprooted by the loaches, so it is a good idea to weight your plants. The pond loach is also peculiar in that it will sometimes bury itself in the substrate during times of stress. This often surprises new owners, as the fish will "disappear" shortly after introduction to the tank only to "reappear" later.{{Citation needed|date=November 2014}}

Because of their alleged appetite for snails, these loaches are commonly perceived as helping to alleviate snail infestations in fish tanks; however, due to their sensitive barbels, and substrate-sifting method of foraging for buried worms and hidden brine shrimp, pond loaches are not nearly as effective against mollusks as the related botiid loaches. Botias possess notably different, downward-pointing snouts with visibly fewer barbels, as they are more active hunters of prey than the bottom-dwelling pond loaches. The botias have evolved perfectly shaped snouts to fit inside a snail's shell.

The pond loaches prefer a water pH of 6.5–8.0, but, as a temperate-climate freshwater species, will tolerate far more acidic conditions, even for extended amounts of time, with little negative reactions. This makes the pond loach a great choice for first-time aquariums and for those who want a hardy fish tank able to withstand a few mistakes. This fish should be kept in groups of at least three, as they like to be in physical contact with each other and feel each other with their barbels when they rest.

There are some hybrid varieties bred in captivity, like the golden dojo and the peppered strain (not to be confused with the peppered loach). Sometimes the pond loach (especially the golden variety) is mistaken for the kuhli loach. The kuhli, however, likes warm tropical temperatures, will tolerate more acidic conditions, and matures at a much smaller {{convert|4|in|cm|spell=in}}. Although these two species have numerous differentiating traits, individual kuhli and pond loaches may resemble each other while young and at the usual age and size of what most fish stores market.

==As food== thumb|''Dojō nabe'', Japanese loach hot pot

The pond loach is a common culinary fish in East Asia, raised on a large scale in fish farming. According to FAO, ''M. anguillicaudatus'' was 30th on the list of most important species in aquaculture, in terms of total weight produced in 2018,<ref>{{cite web |title=FAO Fisheries & Aquaculture Global Production Overview |url=https://www.fao.org/fishery/statistics/global-production/en |website=FAO |access-date=19 November 2021}}</ref> but by individual number it is the most farmed fish in the world.<ref>{{cite journal|vauthors=Mood A, Lara E, Boyland NK, Brooke P|year=2023|title=Estimating global numbers of farmed fishes killed for food annually from 1990 to 2019|journal=Animal Welfare|volume=32|page=e12|doi=10.1017/awf.2023.4|pmc=10936281}}</ref>

In Korea, ''chueo-tang'' (loach soup) is made with pond loach. The Japanese hotpot ''dojō nabe'', a specialty of Asakusa, is also made with this.

In China, pond loach is consumed, especially in Sichuan province, and known as ''niqiu''.<ref>{{Cite journal |last1=Fang |first1=Julian |last2=Fabinyi |first2=Michael |date=2021-07-19 |title=Characteristics and Dynamics of the Freshwater Fish Market in Chengdu, China |journal=Frontiers in Sustainable Food Systems |language=English |volume=5 |doi=10.3389/fsufs.2021.638997 |doi-access=free |bibcode=2021FrSFS...538997F |issn=2571-581X|hdl=10453/149895 |hdl-access=free }}</ref>

==Range== ===Native range=== According to the US Geological Survey, ''M. anguillicaudatus'' is native to eastern Asia from Siberia to Northern Vietnam, including Japan.<ref>{{cite web |title=Pond Loach (''Misgurnus anguillicaudatus'') - Species Profile |url=https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=498 |website=Nonindigenous Aquatic Species|publisher=U.S. Geological Survey |access-date=28 November 2022|last1=Nico|first1=L.|last2=Fuller|first2=P.|last3=Neilson|first3=M.|last4=Larson|first4=J.|last5=Fusaro|first5=A.|last6=Makled|first6=T.H.|last7=Loftus|first7=B.|last8=Bartos|first8=A.|date=13 June 2022 |language=en}}</ref>

===Introduced range===

====Australia==== Imported into Australia in the 1960s as an aquarium species, ''M. anguillicaudatus'' was first detected in the wild in 1980,<ref name=fishesofaustralia /> and its further importation was banned in 1986.<ref name= MDBC>[https://www.mdba.gov.au/sites/default/files/archived/mdbc-NFS-reports/2201_factsheet_alien_oriental_weatherloach.pdf Factsheet alien oriental weatherloach], Murray-Darling Basin Commission. Retrieved 2 February 2023.</ref> ''M. anguillicaudatus'' is a declared Class 1 noxious species in New South Wales,<ref>[https://www.dpi.nsw.gov.au/fishing/aquatic-biosecurity/pests-diseases/freshwater-pests/finfish-species/oriental-weatherloach Oriental weatherloach] NSW Dept of Primary Industries. Retrieved 2 February 2023.</ref> as it has become established in several NSW rivers, including the Murray River<ref name= MDBC /> extending downstream into South Australia.<ref>[https://pir.sa.gov.au/recreational_fishing/rules/species_limits/pest_profile/oriental_weatherloach Oriental Weatherloach], Dept of Primary Industries and Regions, South Australia. Retrieved 2 February 2023.</ref><ref>[https://www.abc.net.au/news/2023-02-01/oriental-weatherloach-pest-found-riverland-sunraysia/101899316 Noxious fish the oriental weatherloach found in the Riverland, causing concern for irrigators], ''ABC News'', 2 February 2023. Retrieved 2 February 2023.</ref>

====United States==== Between 2010 and 2020 ''M. anguillicaudatus'' was found in 10 states of the United States including Alabama and Georgia.<ref name="Morales-2020" /> The Georgia find was in November 2020<ref name="Ginn-2020" /> in McNutt Creek<ref name="Morales-2020" /><ref name="Ginn-2020" /> in Athens<ref name="Morales-2020" /><ref name="Ginn-2020" /> on the border between Clarke and Oconee.<ref name="Morales-2020" /> This indicates eastern Georgia is environmentally suitable for it, and so if not stopped ''M. anguillicaudatus'' is expected to spread through the area.<ref name="Ginn-2020" /> That could include the downstream and adjacent rivers, the Middle Oconee, the North Oconee, the Oconee River itself, the Ocmulgee, and the Altamaha.<ref name="Ginn-2020" />

As of November 2021, according to the U.S. Geological Survey, this species has also been captured from the wild in Illinois (including many captures in the Chicago area), New York, Ohio, Michigan, Washington, Oregon, Maryland, New Jersey, North Carolina, Louisiana, and southern California.<ref>{{cite web |title=Nonindigenous Aquatic Species |url=https://nas.er.usgs.gov/viewer/omap.aspx?SpeciesID=498 |website=nas.er.usgs.gov |access-date=19 November 2021}}</ref>

====Uzbekistan====

''Misgurnus anguillicaudatus'' was first recorded in Uzbekistan in 2022, when specimens were collected from rice paddies adjacent to the lower reaches of the Amu Darya River in the northwestern part of the country. Further collections in 2023 confirmed the presence of both mature adults and juveniles, indicating a well-established, reproducing population<ref name=Sheraliev>{{cite journal|title=First Record of the Non‑native Pond Loach ''Misgurnus anguillicaudatus'' (Cantor, 1842) (Teleostei: Cobitidae) from the Lower Amu Darya River in Uzbekistan|year=2026|journal=Acta Zoologica Bulgarica|doi=10.71424/azb78.1.002968|last1=Sheraliev|first1=Bakhtiyor|volume=78|issue=1|pages=67–74|doi-access=free}}</ref>. The likely invasion pathway is dispersal from the Karakum Canal in neighboring Turkmenistan, where the species had previously been intentionally introduced, via its hydrological connection to the Amu Darya. This represents only the second species of the family Cobitidae recorded from Uzbekistan, joining the native Aral spined loach, ''Sabanejewia aralensis''.

==See also== * Loach * European weather loach * Dojō nabe

==References== {{Reflist|refs= <ref name="Ginn-2020">{{cite web | last=Ginn | first=Alyssa | title=Invasive fish, spider make their way to Athens | website=The Red and Black | date=1970-01-01 | url=http://www.redandblack.com/athensnews/invasive-fish-spider-make-their-way-to-athens/article_27cb570a-3c32-11eb-b7da-ebef8bb1b7ad.html | access-date=2020-12-13}}</ref> <ref name="Morales-2020">{{cite web | title=Invasive fish discovered in Georgia creek | website=UGA Today | date=2020-11-18 | url=http://news.uga.edu/invasive-fish-discovered-in-georgia-creek/ | access-date=2020-12-13}}</ref> }}

==Bibliography== * {{ITIS |id=163978 |taxon=Misgurnus anguillicaudatus |accessdate=30 January 2006}} * {{FishBase|genus=Misgurnus|species=anguillicaudatus|year=2005|month=10}} * [https://web.archive.org/web/20111007194128/http://aqualandpetsplus.com/Oddball,%20Dojo.htm How to Keep Your New Weather Loach] * {{Cite news|title=New Invasive Fish Spreads Through The Ebro Delta|date=2009-01-20|work=Science News|publisher=Science Daily|url=https://www.sciencedaily.com/releases/2009/01/090114095105.htm|access-date=2009-01-20}} * {{Cite journal|last1=Franch|first1=Nati|first2=Miguel|last2=Clavero|first3=Montse |last3=Garrido|first4=Norbert|last4=Gaya|first5=Veronica |last5=Lopez|first6= Quim|last6=Pou-Rovira|first7=Josep|last7=Maria Queral|year=2008|title=On the establishment and range expansion of oriental weatherfish (''Misgurnus anguillicaudatus'') in NE Iberian Peninsula|journal=Biological Invasions|volume=10|issue=8|page=1327|doi=10.1007/s10530-007-9207-9|bibcode=2008BiInv..10.1327F |hdl=10261/46169|s2cid=3236525|hdl-access=free}}

==External links== * [https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=498&Potential=N&Type=1 GLANSIS Species FactSheet]

Category:Misgurnus Category:Commercial fish Category:Freshwater fish of China Category:Freshwater fish of Japan Category:Fish of Korea Category:Fish of Russia Category:Freshwater fish of Taiwan Category:Fish of Vietnam Category:Taxa named by Theodore Edward Cantor Category:Fish described in 1842