Editing Catfish (section)

==Description==
Most catfish are [[bottom feeder]]s. In general, they are negatively [[buoyant]], which means that they usually sink rather than float due to a reduced [[gas bladder]] and a heavy, bony head.<ref name="Bruton"/> Catfish have a variety of body shapes, though most have a cylindrical body with a flattened [[ventrum]] to allow for benthic feeding.<ref name="Bruton"/> A flattened head allows for digging through the substrate, as well as perhaps serving as a [[hydrofoil]]. Some have a mouth that can expand to a large size and contains no [[incisiform]] teeth; catfish generally feed through [[suction]] or gulping rather than biting and cutting prey.<ref name="Bruton"/> Some families, though, notably the [[Loricariidae]] and [[Astroblepidae]], have a [[suckermouth]] that allows them to fasten themselves to objects in fast-moving water.<ref name="Bruton"/>

Catfish do not have [[scale (anatomy)|scale]]s; their bodies are often naked. In some species, their [[mucus]]-covered [[skin]] is used in [[cutaneous respiration]], where the fish breathes through its skin.<ref name="Bruton"/> In [[Armoured catfish|some catfish]], the skin is covered in bony plates called [[scute]]s; some form of body armor appears in various ways within the order. In [[loricarioids]] and in the Asian genus ''[[Sisor]]'', the armor is primarily made up of one or more rows of free [[dermal]] plates. Similar plates are found in large specimens of ''[[Lithodoras]]''. These plates may be supported by [[vertebra]]l [[Process (anatomy)|process]]es, as in [[scoloplacids]] and in ''Sisor'', but the processes never fuse to the plates or form any external armor. By contrast, in the subfamily Doumeinae (family [[Amphiliidae]]) and in hoplomyzontines ([[Aspredinidae]]), the armor is formed solely by expanded vertebral processes that form plates. Finally, the lateral armor of [[doradids]], ''Sisor'', and hoplomyzontines consists of hypertrophied [[lateral line]] ossicles with dorsal and ventral [[lamina (algae)|lamina]].<ref>{{cite journal|author1=Friel, J P  |author2=Lundberg, J G |year=1996|title=''Micromyzon akamai'', gen. et sp. nov., a small and eyeless banjo catfish (Siluriformes: Aspredinidae) from the river channels of the lower Amazon basin|journal=[[Copeia]]|issue=3|pages=641–648|jstor=1447528|volume=1996|doi=10.2307/1447528}}</ref>

[[Juvenile fish|Juvenile]] catfish, like other fish, have relatively large heads, eyes, and posterior median fins in comparison to larger, more mature individuals. These juveniles can be readily placed in their families, particularly those with highly derived fin or body shapes; in some cases, identification of the genus is possible. As far as known for most catfish, features that are often characteristic of species, such as mouth and fin positions, fin shapes, and barbel lengths, show little difference between juveniles and adults. For many species, pigmentation pattern is also similar in juveniles and adults. Thus, juvenile catfish generally resemble and develop smoothly into their adult form without distinct juvenile specializations. Exceptions to this are the ariid catfish, where the young retain yolk sacs late into juvenile stages, and many pimelodids, which may have elongated barbels and fin filaments or coloration patterns.<ref>{{cite journal|title=First description of small juveniles of the primitive catfish ''Diplomystes'' (Siluriformes: Diplomystidae)|first=John G.|last=Lundberg|author2=Berra, Tim M.|author3=Friel, John P.|journal=Ichthyol. Explor. Freshwaters|volume=15|issue=1|pages=71–82|year=2004|url=https://mansfield.osu.edu/assets/mansfield/tberra/pdf/Diplomystes.pdf|access-date=27 March 2023|archive-date=11 December 2021|archive-url=https://web.archive.org/web/20211211152811/https://mansfield.osu.edu/assets/mansfield/tberra/pdf/Diplomystes.pdf|url-status=live}}</ref>

===Sensory organs===
{{Multiple image
| image1            = BARBEL (PSF).png
| image2            = Channelcat.jpg
| footer            = The [[channel catfish]] has four pairs of [[barbel (anatomy)|barbels]].
| direction         = vertical
}}
The [[Fish anatomy#Head|maxilla]] is a [[Alveolar process|tooth-bearing bone]] in vertebrates, and modified in [[Neopterygii|neopterygian]] fish to facilitate the protrusion of the mouth and enable [[suction feeding]]. Catfish, despite being a group of neopterygians, reduced the maxilla into a support for the maxillary [[barbel (anatomy)|barbels]];<ref name="BarbMobe"/> this means that they are unable to protrude their mouths as other fish such as [[carp]].<ref name="Bruton"/> Catfish barbels typically occur in pairs, and up to four pairs of barbels may be present in soe species; these being the nasal, maxillary (on each side of mouth), and two pairs of "chin" barbels termed the internal and external [[Mandible|mandibular]] barbel, though the various families often have fewer pairs, some species may have [[wikt:branched|branched]] or duplicated barbel pairs, and a number of families only have extremely reduced maxillary barbels. The [[Palatine bone|palatine]]-maxillary system is responsible for moving the maxillary barbels; it is a system of ligaments and muscles centred on these two skeletal elements.<ref name="BarbMobe">{{cite book |author=Rui Diogo
|author2=M. Chardon|author3=Pierre Vandewalle|title=Catfishes|chapter=Functional Morphology of Catfishes: Movements of Barbels. |date=January 2003 |publisher=Science Publishers, Inc. |pages=203-220 |edition=1 |url=https://www.researchgate.net/publication/259529073_Functional_Morphology_of_Catfishes_Movements_of_Barbels |access-date=17 May 2025}}</ref><ref>{{cite journal |last1=Diogo |first1=Rui |last2=Chardon |first2=M. |title=Adaptive transformation of the palatine-maxillary system in catfish: Increased mobility of the maxillary barbel. In: Kapoor, B.G. & T.J. Hara (eds.), Sensory Biology of Jawed Fishes |journal=New Insights, Science Publishers |date=January 2001 |url=https://www.researchgate.net/publication/264340157_DIOGO_R_M_CHARDON_2001_Adaptive_transformation_of_the_palatine-maxillary_system_in_catfish_Increased_mobility_of_the_maxillary_barbel_In_Kapoor_BG_TJ_Hara_eds_Sensory_Biology_of_Jawed_Fishes_-_New_Ins |access-date=17 May 2025}}</ref> If severed, the barbels [[Regeneration (biology)|grow back]] over time, but the maxillary barbels cannot regenerate if their [[Basal (anatomy)|basal element]] (the maxilla) is lost.<ref>{{cite journal |author=Yu-Lin Zhou |author2= Jun-Jie Wu |author3=Gao-Rui Gong |author4=Min Liu |author5=Zhi Li |author6=Xin-Feng Guo |author7=Wen-Yu Wei |author8=Xiao-Juan Zhang |author9=Jie Mei |author10=Li Zhou |author11=Zhong-Wei Wang |author12=Jian-Fang Gui |title=Barbel regeneration and function divergence in red-tail catfish (Hemibagrus wyckioides) based on the chromosome-level genomes and comparative transcriptomes |date=31 March 2023 |volume=232 |doi=10.1016/j.ijbiomac.2023.123374 |pmid=123374 |url=https://www.sciencedirect.com/science/article/pii/S014181302300260X/pdfft?md5=1bc2843ab8686306015a62c29d159fbf&pid=1-s2.0-S014181302300260X-main.pdf |access-date=17 May 2025}}</ref><ref>{{cite journal |last1=Griswold |first1=Ruth-Marie E. |title=Investigation of barbel regeneration in the catfish Ameiurus nebulosus |journal=Colby College |date=1972 |url=https://digitalcommons.colby.edu/cgi/viewcontent.cgi?article=1107&context=seniorscholars |access-date=17 May 2025}}</ref>

Many larger catfish also have [[chemoreceptor]]s across their entire bodies (especially the barbels), which means they "taste" anything they touch, and "smell" any chemicals in the water. "In catfish, [[gustation]] plays a primary role in the orientation and location of food".<ref>Atema, Jelle (1980) [https://books.google.com/books?id=TZbRp0z5-p0C&pg=PA57 "Chemical senses, chemical signals, and feeding behavior in fishes"] pp. 57–101. In: Bardach, JE ''Fish behavior and its use in the capture and culture of fishes'', The WorldFish Center, {{ISBN|978-971-02-0003-0}}.</ref> Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are generally small. In fact, many species of catfish have [[Atrophy|lost]] them entirely as they adapted to underground environments, becoming [[cavefish]]. Like other [[ostariophysan]]s, they are characterized by the presence of a [[Weberian apparatus]].<ref name="Nelson"/> Their well-developed Weberian apparatus and reduced gas bladder allow for improved [[hearing (sense)|hearing]] and sound production.<ref name="Bruton"/>

===Fin spines and toxins===
[[File:Image-Striped eel catfish2.jpg|thumb|A sting from the striped eel catfish, ''[[Plotosus lineatus]]'', may be fatal. These are juveniles]]
All catfish other than members of the [[Malapteruridae]] ([[electric catfish]]), possess a strong, hollow, bony, leading spine-like ray on their [[dorsal fin|dorsal]] and [[pectoral fin]]s. As a defense, these spines may be locked into place so that they stick outwards, enabling them to inflict severe wounds.<ref name=tol/> In numerous catfish species, these fin rays can be used to deliver a stinging [[protein]] if the fish is irritated;<ref name=fin>{{cite web| url = http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/channel_catfish.htm| archive-url = https://web.archive.org/web/20060603225626/http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/channel_catfish.htm| archive-date = 3 June 2006|title=Channel Catfish |access-date=2 December 2006|publisher=Fairfax County Public Schools}}</ref> as many as half of all catfish species may be venomous in this fashion, making the Siluriformes overwhelmingly the vertebrate order with the largest number of venomous species.<ref>{{cite journal |last1=Wright |first1=Jeremy J |title=Diversity, phylogenetic distribution, and origins of venomous catfishes |journal=BMC Evolutionary Biology |date=4 December 2009 |volume=9 |issue=1 |pages=282 |doi=10.1186/1471-2148-9-282 |pmid=19961571 |pmc=2791775 |bibcode=2009BMCEE...9..282W |doi-access=free }}</ref> This [[venom]] is produced by [[gland]]ular cells in the [[epidermal]] tissue covering the spines.<ref name="Nelson"/> In members of the family [[Plotosidae]] and of the genus ''[[Heteropneustes]]'', this protein is so strong it may hospitalize humans who receive a sting; in ''[[Plotosus lineatus]]'', the stings can be lethal.<ref>{{FishBase|genus=Plotosus|species=lineatus|month=November|year=2014}}</ref><ref name="Nelson"/> The dorsal- and pectoral-fin spines are two of the most conspicuous features of siluriforms, and differ from those in other fish groups.<ref name='Ballen'>{{cite journal|author1=Ballen, Gustavo A.|author2=De Pinna, Mario C. C.|title=A standardized terminology of spines in the order Siluriformes (Actinopterygii: Ostariophysi)|year=2022|journal=Zoological Journal of the Linnean Society|volume=194|issue=2|pages=601–625|doi=10.1093/zoolinnean/zlab008|url=https://doi.org/10.1093/zoolinnean/zlab008|access-date=10 February 2022|archive-date=23 September 2023|archive-url=https://web.archive.org/web/20230923095540/https://academic.oup.com/zoolinnean/article/194/2/601/6191677|url-status=live}}</ref> Despite the widespread use of the spines for taxonomic and phylogenetic studies the fields have struggled to effectively use the information due to a lack of consistency in the nomenclature, with a general standard for the descriptive anatomy of catfish spines proposed in 2022 to try and resolve this problem.<ref name='Ballen'/>

===Internal anatomy===
{{Multiple image
| image1            = Blue catfish skeleton.jpg
| direction         = vertical
| caption1          = Blue catfish (''[[Blue catfish|Ictalurus furcatus]])'' skeleton, [[Museum of Osteology]]
| image2            = Kryptopterus 2.jpg
| caption2          = The internal organs of [[glass catfish]] (such as ''[[Kryptopterus vitreolus]]'') are visible through their transparent bodies
| align             = left
}}

In many catfish, the "humeral process" is a bony process extending backward from the [[pectoral girdle]] immediately above the base of the pectoral fin. It lies beneath the skin, where its outline may be determined by dissecting the skin or probing with a needle.<ref>{{cite web|url=http://filaman.ifm-geomar.de/Glossary/Glossary.cfm?TermEnglish=humeral%20process|archive-url=https://web.archive.org/web/20071217212539/http://filaman.ifm-geomar.de/Glossary/Glossary.cfm?TermEnglish=humeral%20process|archive-date=17 December 2007|title=Term : humeral process|publisher=[[FishBase]]|year=2007}}</ref>

The [[retina]]e of catfish are composed of single [[cone cell|cone]]s and large [[rod cell|rod]]s. Many catfish have a [[tapetum lucidum]], which may help enhance [[photon]] capture and increase low-light sensitivity. [[Double cone (biology)|Double cone]]s, though present in most [[teleost]]s, are absent from catfish.<ref name="Douglas">{{cite journal|last=Douglas|first=Ron H.|author2=Collin, Shaun P.|author3=Corrigan, Julie|date=15 November 2002|url=http://jeb.biologists.org/cgi/reprint/205/22/3425|title=The eyes of suckermouth armoured catfish (Loricariidae, subfamily Hypostomus): pupil response, lenticular longitudinal spherical aberration and retinal topography|publisher=The Journal of Experimental Biology|volume=205|issue=22|pages=3425–3433|journal=Journal of Experimental Biology|doi=10.1242/jeb.205.22.3425|pmid=12364396|bibcode=2002JExpB.205.3425D |access-date=9 June 2007|archive-date=30 September 2007|archive-url=https://web.archive.org/web/20070930044830/http://jeb.biologists.org/cgi/reprint/205/22/3425|url-status=live}}</ref>

====Sexual characters====
[[Sexual dimorphism]] is reported in about half of all families of catfish.<ref>{{cite journal|url=http://www.mapress.com/zootaxa/2006f/zt01125p056.pdf |archive-url=https://web.archive.org/web/20061031234339/http://www.mapress.com/zootaxa/2006f/zt01125p056.pdf |archive-date=2006-10-31 |url-status=live|title=''Synodontis acanthoperca'', a new species from the Ogôoué River system, Gabon with comments on spiny ornamentation and sexual dimorphism in mochokid catfishes (Siluriformes: Mochokidae)|first=John P.|last=Friel|author2=Vigliotta, Thomas R.|journal=[[Zootaxa]]|volume=1125|pages=45–56|year=2006|access-date=22 June 2009|doi=10.11646/zootaxa.1125.1.3}}</ref> The modification of the [[anal fin]] into an [[penis|intromittent organ]] (in internal fertilizers) as well as accessory structures of the reproductive apparatus (in both internal and external fertilizers) have been described in species belonging to 11 different families.<ref name="Mazzoldi">{{cite journal|title=Variation of male reproductive apparatus in relation to fertilization modalities in the catfish families Auchenipteridae and Callichthyidae (Teleostei: Siluriformes)|first=C.|last=Mazzoldi|author2=Lorenzi, V. |author3=Rasotto, M. B. |journal=Journal of Fish Biology|year=2007|volume=70|issue=1 |pages=243–256|doi=10.1111/j.1095-8649.2006.01300.x|bibcode=2007JFBio..70..243M }}</ref>

The anatomical organization of the [[testicle|testis]] in catfish is variable among the families of catfish, but the majority of them present fringed testis: Ictaluridae, Claridae, Auchenipteridae, Doradidae, Pimelodidae, and Pseudopimelodidae.<ref name="Barros"/> In the testes of some species of Siluriformes, organs and structures such as a spermatogenic cranial region and a secretory caudal region are observed, in addition to the presence of seminal vesicles in the caudal region.<ref name="Brito"/> The total number of fringes and their length are different in the [[Caudal (anatomical term)|caudal]] and [[cranial]] portions between species.<ref name="Barros">{{cite journal|title=Reproductive apparatus and gametogenesis of ''Lophiosilurus alexandri'' Steindachner (Pisces, Teleostei, Siluriformes)|first=Marcelo D. M.|last=Barros|author2=Guimarães-Cruz, Rodrigo J. |author3=Veloso-Júnior, Vanderlei C. |author4= Santos, José E. dos |journal=Revista Brasileira de Zoologia|volume=24|issue=1|pages=213–221|year=2007|doi=10.1590/S0101-81752007000100028|doi-access=free}}</ref> Fringes of the caudal region may present tubules, in which the lumen is filled by secretion and [[Spermatozoon|spermatozoa]].<ref name="Barros"/> Spermatocysts are formed from cytoplasmic extensions of [[Sertoli cell]]s; the release of spermatozoa is allowed by breaking of the cyst walls.<ref name="Barros"/>

The occurrence of [[seminal vesicle]]s, in spite of their interspecific variability in size, gross morphology, and function, has not been related to the mode of fertilization. They are typically paired, multichambered, and connected with the [[sperm duct]], and have been reported to play glandular and storage functions. Seminal vesicle secretion may include [[steroid]]s and steroid [[glucuronide]]s, with [[Hormone|hormonal]] and [[Pheromone|pheromonal]] functions, but it appears to be primarily constituted of [[mucoprotein]]s, acid [[mucopolysaccharide]]s, and [[phospholipid]]s.<ref name="Mazzoldi"/>

Fish [[Ovary|ovaries]] may be of two types - gymnovarian or cystovarian. In the first type, the [[oocyte]]s are released directly into the [[coelom]]ic cavity and then eliminated (released outside the body). In the second type, the oocytes are conveyed to the exterior through the [[oviduct]].<ref name="Brito"/> Many catfish are cystovarian in type, including ''[[Pseudoplatystoma corruscans]]'', ''[[Pseudoplatystoma fasciatum|P. fasciatum]]'', ''[[Lophiosilurus alexandri]]'', and ''[[Loricaria lentiginosa]]''.<ref name="Barros"/><ref name="Brito">{{cite journal|title=Reproduction of the surubim catfish (Pisces, Pimelodidae) in the São Francisco River, Pirapora Region, Minas Gerais, Brazil|last=Brito|first=M.F.G.|author2=Bazzoli, N.|journal=Arquivo Brasileiro de Medicina Veterinária e Zootecnia|volume=55|issue=5|year=2003|doi=10.1590/S0102-09352003000500018|page=624|doi-access=free}}</ref>

===Size===
[[File:Bagarius yarrelli India.png|thumb|Giant ''[[Bagarius yarrelli]]'' (goonch) caught in India. Some goonch in the Kali River grow large enough to supposedly attack humans and [[water buffalo]]]]
Catfish have one of the largest ranges in size within a single order of [[Actinopterygii|bony fish]].<ref name="Bruton"/> Many catfish have a maximum length of under {{convert|12|cm|in|abbr=on}}.<ref name="Nelson" /> Some of the smallest species of the [[Aspredinidae]] and [[Trichomycteridae]] reach sexual maturity at only {{convert|1|cm|in|abbr=on}}.<ref name=tol/>

The [[wels catfish]], ''Silurus glanis'', and the much smaller related [[Aristotle's catfish]], are the only catfish indigenous to [[Europe]]; the former ranges throughout Europe, and the latter is restricted to [[Greece]]. [[Mythology]] and literature record wels catfish of astounding proportions yet are to be proven scientifically. The typical size of the species is about {{convert|1.2–1.6|m|ft|abbr=on}}, and fish more than {{convert|2|m|ft|abbr=on}} are rare. However, they are known to exceed {{convert|2.5|m|ft|abbr=on}} in length and {{convert|100|kg|lb|abbr=on}} in weight. In July 2009, a catfish weighing {{convert|88|kg|lb}} was caught in the [[River Ebro]], Spain, by an 11-year-old British schoolgirl.<ref>{{cite news| url=https://www.telegraph.co.uk/news/newstopics/howaboutthat/5834754/Schoolgirl-nets-9ft-monster-fish.html |archive-url=https://ghostarchive.org/archive/20220111/https://www.telegraph.co.uk/news/newstopics/howaboutthat/5834754/Schoolgirl-nets-9ft-monster-fish.html |archive-date=11 January 2022 |url-access=subscription |url-status=live | work=[[The Daily Telegraph]] | location=London | title=Schoolgirl nets 9ft monster fish | date=15 July 2009 | access-date=28 April 2010}}{{cbignore}}</ref>

In North America, the largest ''[[Ictalurus furcatus]]'' (blue catfish) caught in the [[Missouri River]] on 20 July 2010, weighed {{convert|59|kg|lb|abbr=on}}. The largest [[flathead catfish]], ''Pylodictis olivaris'', ever caught was in [[Independence, Kansas]], weighing {{convert|56|kg|lb|abbr=on}}. The biggest flathead catfish caught was by Ken Paulie in the [[Elk City Reservoir]] in Kansas, US on 19 May 1998 weighing {{convert|55.79|kg|lboz|abbr=on}}, which was certified by the International Game Fish Association [[IGFA]].<ref>{{cite web |url=http://wrec.igfa.org/ |title=IGFA World Records |publisher=International Game Fish Association |access-date=1 November 2015 |archive-date=1 November 2015 |archive-url=https://web.archive.org/web/20151101064327/http://wrec.igfa.org/ |url-status=live }}</ref>

These records pale in comparison to a [[Mekong giant catfish]] caught in northern [[Thailand]] on 1 May 2005, and reported to the press almost 2 months later, that weighed {{convert|293|kg|lb}}. This is the largest giant Mekong catfish caught since Thai officials started keeping records in 1981.<ref name=Mekong>{{cite web|url=http://news.nationalgeographic.com/news/2005/06/0629_050629_giantcatfish.html|title=Grizzly Bear-Size Catfish Caught in Thailand|date=29 June 2005|access-date=14 July 2006|publisher=National Geographic News|archive-date=30 June 2005|archive-url=https://web.archive.org/web/20050630233848/http://news.nationalgeographic.com/news/2005/06/0629_050629_giantcatfish.html|url-status=dead}}</ref> Also in Asia, [[Jeremy Wade]] caught a {{convert|75.5|kg|lb|1|adj=on}} [[Bagarius yarrelli|goonch]] following [[Kali River goonch attacks|three fatal attacks on humans]] in the [[Sharda River|Kali River]] on the [[India]]-[[Nepal]] border. Wade was of the opinion that the offending fish must have been significantly larger than this to have taken an 18-year-old boy, as well as a [[water buffalo]].{{citation needed|reason=This claim needs a reliable source.|date=March 2020}}

Piraíba ''([[Brachyplatystoma filamentosum]])'', a [[goliath catfish]], can grow exceptionally large and are native to the Amazon Basin. They can occasionally grow to {{convert|200|kg|lb|abbr=on}}, as evidenced by numerous catches. Deaths from being swallowed by these fish have been reported in the region.