Characiformes
{{Short description|Order of fishes}}
{{Automatic taxobox
| fossil_range = {{Fossil range|Santonian|recent|earliest=Cenomanian}} Possible Cenomanian occurrence
| image = Fish fauna of the Uberaba River (3486594).jpg
| image_upright = 1.2
| image_caption = Diversity of American characiforms from the Uberaba River basin
| image2 =
| image2_caption =
| taxon = Characiformes
| authority = Regan, 1911
| subdivision_ranks = Suborders
| subdivision = * Citharinoidei
| type_species = Charax gibbosus
| type_species_authority = Linnaeus, 1758
}}
Characiformes {{IPAc-en|ˈ|k|æ|r|ə|s|ᵻ|f|ɔːr|m|iː|z}} is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.{{cite book | title = Fishes of the World | last = Nelson | first = Joseph, S. | publisher = John Wiley & Sons, Inc. | year = 2006 | isbn = 0-471-25031-7}}; Buckup P.A.: "Relationships of the Characidiinae and phylogeny of characiform fishes (Teleostei: Ostariophysi)", Phylogeny and Classification of Neotropical Fishes, L.R. Malabarba, R.E. Reis, R.P. Vari, Z.M. Lucena, eds. (Porto Alegre: Edipucr) 1998:123-144.
Taxonomy
The Characiformes form part of a series called the Otophysi within the superorder Ostariophysi. The Otophysi contain three other orders, Cypriniformes, Siluriformes, and Gymnotiformes. The Characiformes form a group known as the Characiphysi with the Siluriformes and Gymnotiformes. The order Characiformes is the sister group to the orders Siluriformes and Gymnotiformes, though this has been debated in light of recent molecular evidence.
Originally, the characins were all grouped within a single family, the Characidae. Since then, 18 different families have been separated out. However, classification varies somewhat, and the most recent (2011) study confirms the circumscribed Characidae as monophyletic.[http://www.biomedcentral.com/1471-2148/11/275 Claudio Oliveira, Gleisy S Avelino, Kelly T Abe, Tatiane C Mariguela, Ricardo C Benine, Guillermo Ortí, Richard P Vari and Ricardo M Corrêa e Castro,"Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling", BMC Evolutionary Biology 2011, 11:275)]. Currently, 18 families, about 270 genera, and at least 1674 species are known.
The suborder Citharinoidei, which contains the families Distichodontidae and Citharinidae, is considered the sister group to the rest of the characins, suborder Characoidei.{{cite journal |title=The biogeography of otophysan fishes (Ostariophysi: Otophysi): a new appraisal |last=Briggs |first=John C. |journal=Journal of Biogeography |year=2005 |volume=32 |issue=2 |pages=287–294 |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2699.2004.01170.x |format=PDF |doi=10.1111/j.1365-2699.2004.01170.x|bibcode=2005JBiog..32..287B |s2cid=84010604 |url-access=subscription }} This group has a very ancient divergence from the rest of the Characiformes, dating back to the Early Cretaceous or earlier, and it has been suggested that it be better treated as its own order, the Cithariniformes.{{Cite journal |last1=Near |first1=Thomas J. |last2=Thacker |first2=Christine E. |date=2024-04-18 |title=Phylogenetic Classification of Living and Fossil Ray-Finned Fishes (Actinopterygii) |journal=Bulletin of the Peabody Museum of Natural History |volume=65 |issue=1 |doi=10.3374/014.065.0101 |issn=0079-032X|doi-access=free }}
Evolution
The Characiformes likely first originated and diversified on the supercontinent of West Gondwana (composed of modern Africa and South America) during the Cretaceous period, though fossils are poorly known. During the Cretaceous Period, the rift between South America and Africa would be forming; this may explain the contrast in diversity between the two continents. Their low diversity in Africa may explain why some primitive fish families and the Cypriniformes coexist with them whereas they are absent in South America, where these fish may have been driven extinct. The characiforms had not spread into Africa soon enough to also reach the land connection between Africa and Asia. The earliest they could have spread into Central America was the late Miocene.
= Fossils =
File:Lignobrycon ligniticus (P9012).tif, a fossil characiform from the Oligocene of Brazil]]
The earliest characiform fossils date back to the Late Cretaceous, around the Santonian.{{Cite journal |last1=Szabó |first1=Márton |last2=Ősi |first2=Attila |date=2017-09-01 |title=The continental fish fauna of the Late Cretaceous (Santonian) Iharkút locality (Bakony Mountains, Hungary) |url=https://akjournals.com/view/journals/24/60/2/article-p230.xml |journal=Central European Geology |language=en-US |volume=60 |issue=2 |pages=230–287 |doi=10.1556/24.60.2017.009 |bibcode=2017CEJGl..60..230S |issn=1789-3348|hdl=10831/67493 |hdl-access=free }} Other fossil teeth date back to the Cenomanian of Morocco, but it has been suggested that these teeth may be of early ginglymodians. Previously, the oldest characiform was assumed to be Santanichthys of the Early Cretaceous (Albian Age) of Brazil. This presumably marine taxon was used as evidence of characiformes potentially having marine origins.{{cite journal |last=Filleul |first=Arnaud |author2=John G. Maisey |date=2004-10-28 |title=Redescription of Santanichthys diasii (Otophysi, Characiformes) from the Albian of the Santana Formation and comments on its implications for Otophysan relationships |url=https://zenodo.org/record/5382553 |journal=American Museum Novitates |issue=3455 |pages=1–22 |doi=10.1206/0003-0082(2004)455<0001:ROSDOC>2.0.CO;2 |s2cid=85575649 |hdl-access=free |hdl=2246/2765}} However, more recent studies indicate that Santanaichthys is likely a basal otophysan rather than a characiform. Similarly, Salminops from Spain and Sorbinicharax from Italy, previously also considered potential marine characiforms, are now thought to have no characiform affinities and are considered indeterminate teleosts. Given this, there is no paleontological support for characiforms having marine origins.{{Cite journal |last1=Capobianco |first1=Alessio |last2=Friedman |first2=Matt |date=2019 |title=Vicariance and dispersal in southern hemisphere freshwater fish clades: a palaeontological perspective |url=https://onlinelibrary.wiley.com/doi/10.1111/brv.12473 |journal=Biological Reviews |language=en |volume=94 |issue=2 |pages=662–699 |doi=10.1111/brv.12473 |pmid=30338909 |hdl=2027.42/148368 |issn=1464-7931|hdl-access=free }}{{Cite journal |last1=Mayrinck |first1=Diogo |last2=Brito |first2=Paulo M. |last3=Meunier |first3=François J. |last4=Alvarado-Ortega |first4=Jesus |last5=Otero |first5=Olga |date=2017-08-28 |title=†Sorbinicharax verraesi: An unexpected case of a benthic fish outside Acanthomorpha in the Upper Cretaceous of the Tethyan Sea |journal=PLOS ONE |language=en |volume=12 |issue=8 |pages=e0183879 |doi=10.1371/journal.pone.0183879 |doi-access=free |issn=1932-6203 |pmc=5573274 |pmid=28846739|bibcode=2017PLoSO..1283879M }}
Uniquely, Late Cretaceous characiform fossils are found significantly north of their modern distribution. Indeterminate characiform teeth are known from the Santonian of Hungary and Maastrichtian of France, which have a large, multi-cusped appearance reminiscent of African alestids.{{Cite journal |last1=Szabó |first1=Márton |last2=Ősi |first2=Attila |date=2017-09-01 |title=The continental fish fauna of the Late Cretaceous (Santonian) Iharkút locality (Bakony Mountains, Hungary) |url=https://akjournals.com/view/journals/24/60/2/article-p230.xml |journal=Central European Geology |language=en-US |volume=60 |issue=2 |pages=230–287 |doi=10.1556/24.60.2017.009 |bibcode=2017CEJGl..60..230S |issn=1789-3348|hdl=10831/67493 |hdl-access=free }} Similarly, two Campanian freshwater characiform genera, Primuluchara and Eotexachara, are known from North America, with Primuluchara having a very wide distribution across Laramidia, ranging from Texas to as far north as southern Canada (Dinosaur Park Formation). It is likely that the warmer conditions of the Late Cretaceous allowed early characins to range farther north than the present day, with African characins colonizing Europe and South American characins colonizing North America. Early characins may have had some level of salt tolerance, allowing for such colonizations to take place.{{Cite journal |last=Wick |first=Steven L. |date=2021-12-01 |title=New early Campanian characiform fishes (Otophysi: Characiformes) from West Texas support a South American origin for known Late Cretaceous characiforms from North America |url=https://www.sciencedirect.com/science/article/pii/S019566712100241X |journal=Cretaceous Research |volume=128 |pages=104993 |doi=10.1016/j.cretres.2021.104993 |bibcode=2021CrRes.12804993W |issn=0195-6671|url-access=subscription }} Within their modern distribution, a number of modern South American characin families have their earliest occurrences in the Maastrichtian of Bolivia, with isolated teeth and skeletal elements identifiable to Acestrorhynchidae, Characidae, and Serrasalmidae.
Characins appear to have inhabited Europe into the Paleogene, with fossil teeth reminiscent of Alestes known from the Early Eocene of Spain.{{Cite journal |last=Zarzuelo |first=Antonio de la Peña |date=1996 |title=Characid Teeth from the Lower Eocene of the Ager Basin (Lérida, Spain): Paleobiogeographical Comments |url=https://www.jstor.org/stable/1447544 |journal=Copeia |volume=1996 |issue=3 |pages=746–750 |doi=10.2307/1447544 |issn=0045-8511|url-access=subscription }} Eurocharax Gaudant, 1980 is known from a fully-articulated specimen from the Oligocene of France, and appears to represent an estuarine taxon, although its phylogenetic position needs revision.{{Cite journal |last=Gaudant |first=Jean |date=1980-01-01 |title=Eurocharax Tourainei nov. gen., nov. sp. (poisson teleosteen, Ostariophysi): Nouveau Characidae fossile des «Calcaires a Bythinies du Var |url=https://www.sciencedirect.com/science/article/abs/pii/S0016699580800519 |journal=Geobios |volume=13 |issue=5 |pages=683–703 |doi=10.1016/S0016-6995(80)80051-9 |issn=0016-6995|url-access=subscription }}{{Citation |last=Cavender |first=T. M. |title=The fossil record of the Cyprinidae |date=1991 |work=Cyprinid Fishes: Systematics, biology and exploitation |pages=34–54 |editor-last=Winfield |editor-first=Ian J. |url=https://link.springer.com/chapter/10.1007/978-94-011-3092-9_2 |access-date=2025-04-24 |place=Dordrecht |publisher=Springer Netherlands |language=en |doi=10.1007/978-94-011-3092-9_2 |isbn=978-94-011-3092-9 |editor2-last=Nelson |editor2-first=Joseph S.|url-access=subscription }} Two other alleged Eocene European characids, Prohydrocyon Piton, 1938 and Procharacinus Piton, 1938 from France, lack a Weberian apparatus and are very likely not characins, and instead may be related to the enigmatic Thaumaturus.{{Cite journal |last=Novacek |first=Michael J. |last2=Marshall |first2=Larry G. |date=1976 |title=Early Biogeographic History of Ostariophysan Fishes |url=https://www.jstor.org/stable/1443767 |journal=Copeia |volume=1976 |issue=1 |pages=1–12 |doi=10.2307/1443767 |issn=0045-8511|url-access=subscription }}
Taxonomy
File:Citharinus congicus.jpg is a member of the most basal characiform lineage]]
File:Hydrocynus goliath Gifu.jpg, from Africa, is one of the largest species in the order]]
File:Characiformes in the Munim River Basin.jpg basin]]
File:Peixes da planície de inundação do alto rio Paraná (3678425).png basin]]
The following classification is based on Eschmeyer's Catalog of Fishes (2025),{{Cite web |last=Fricke |first=R. |last2=Eschmeyer |first2=W. N. |last3=Van der Laan |first3=R. |date=2025 |title=ESCHMEYER'S CATALOG OF FISHES: CLASSIFICATION |url=https://www.calacademy.org/eschmeyers-catalog-of-fishes-classification |access-date=2025-02-10 |website=California Academy of Sciences |language=en}} with suprafamilial divisions based on Betancur et al (2018) & Melo et al (2022):{{Cite journal |last=Betancur-R. |first=Ricardo |last2=Arcila |first2=Dahiana |last3=Vari |first3=Richard P. |last4=Hughes |first4=Lily C. |last5=Oliveira |first5=Claudio |last6=Sabaj |first6=Mark H. |last7=Ortí |first7=Guillermo |date=2019-02-01 |title=Phylogenomic incongruence, hypothesis testing, and taxonomic sampling: The monophyly of characiform fishes* |url=https://academic.oup.com/evolut/article-abstract/73/2/329/6882143?redirectedFrom=fulltext |journal=Evolution |volume=73 |issue=2 |pages=329–345 |doi=10.1111/evo.13649 |issn=0014-3820|url-access=subscription }}{{Cite journal |last=Melo |first=Bruno F |last2=Sidlauskas |first2=Brian L |last3=Near |first3=Thomas J |last4=Roxo |first4=Fabio F |last5=Ghezelayagh |first5=Ava |last6=Ochoa |first6=Luz E |last7=Stiassny |first7=Melanie L J |last8=Arroyave |first8=Jairo |last9=Chang |first9=Jonathan |last10=Faircloth |first10=Brant C |last11=MacGuigan |first11=Daniel J |last12=Harrington |first12=Richard C |last13=Benine |first13=Ricardo C |last14=Burns |first14=Michael D |last15=Hoekzema |first15=Kendra |date=2022-01-01 |title=Accelerated Diversification Explains the Exceptional Species Richness of Tropical Characoid Fishes |url=https://academic.oup.com/sysbio/article/71/1/78/6294320 |journal=Systematic Biology |volume=71 |issue=1 |pages=78–92 |doi=10.1093/sysbio/syab040 |issn=1063-5157|pmc=9034337 }}
- Order Characiformes
- Suborder Citharinoidei
- Family Citharinidae Günther, 1864 (citharinids)
- Family Distichodontidae Günther, 1864 (distichodontids)
- Suborder Characoidei
- Superfamily Crenuchoidea
- Family Crenuchidae Günther 1864 (crenuchids)
- Superfamily Alestoidea
- Family Alestidae Cockerell, 1910 (African tetras)
- Family Lepidarchidae Melo & Stiassny, 2024
- Family Hepsetidae Hubbs, 1939 (African pikes)
- Superfamily Erythrinoidea (=Curimatoidea, Anostomoidea){{Cite journal |last=Dillman |first=Casey B. |last2=Sidlauskas |first2=Brian L. |last3=Vari |first3=Richard P. |date=2016 |title=A morphological supermatrix-based phylogeny for the Neotropical fish superfamily Anostomoidea (Ostariophysi: Characiformes): phylogeny, missing data and homoplasy |url=https://onlinelibrary.wiley.com/doi/full/10.1111/cla.12127 |journal=Cladistics |language=en |volume=32 |issue=3 |pages=276–296 |doi=10.1111/cla.12127 |issn=1096-0031}}
- Family Tarumaniidae de Pinna, Zuanon, Rapp Py-Daniel & Petry, 2017 (muckfishes)
- Family Erythrinidae Valenciennes, 1847 (trahiras)
- Family Parodontidae Eigenmann, 1910 (darter tetras)
- Family Cynodontidae Eigenmann, 1903 (sabertoothed characids)
- Family Serrasalmidae Bleeker, 1859 (piranhas and allies)
- Family Hemiodontidae Bleeker, 1859 (hemiodontids)
- Family Anostomidae Günther, 1864 (toothed headstanders)
- Family Chilodidae Eigenmann, 1910 (headstanders)
- Family Curimatidae Gill, 1858 (toothless characiforms)
- Family Prochilodontidae Eigenmann, 1909 (bocachicos)
- Superfamily Characoidea
- Family Lebiasinidae Gill, 1889 (lebiasinids)
- Family Ctenoluciidae Schultz, 1944 (pike characids)
- Family Chalceidae Fowler, 1958 (tucanfishes)
- Family Triportheidae Fowler, 1940 (hatchet characins)
- Family Gasteropelecidae Bleeker, 1859 (freshwater hatchetfishes)
- Family Bryconidae Eigenmann, 1912 (bryconids)
- Family Iguanodectidae Eigenmann, 1909 (iguanodectids)
- Family Acestrorhynchidae Eigenmann, 1912 (freshwater barracudas and biting tetras)
- Family Spintherobolidae Mirande, 2019 (piquiras)
- Family Stevardiidae Gill, 1858 (stevardiids)
- Family Characidae Latreille, 1825 (characids)
- Family Acestrorhamphidae Eigenmann, 1907 (American tetras)
- incertae sedis genera (Characidae sensu lato):
- Genus Dectobrycon Zarske & Géry, 2006
- Genus Gymnocharacinus Steindachner, 1903
- Genus Leptobrycon Eigenmann, 1915
- Genus Mixobrycon Eigenmann, 1915
- Genus Oligobrycon Eigenmann, 1915
- Genus Schultzites Géry, 1964
- Genus Scissor Günther, 1864
- Genus Serrabrycon Vari, 1986
- Genus Thrissobrycon Böhlke, 1953
= Fossil taxa =
- Order Characiformes
- Genus †Eotexachara Wick, 2021 (Late Cretaceous of Texas, US){{Cite journal |last=Wick |first=Steven L. |date=2021-12-01 |title=New early Campanian characiform fishes (Otophysi: Characiformes) from West Texas support a South American origin for known Late Cretaceous characiforms from North America |url=https://linkinghub.elsevier.com/retrieve/pii/S019566712100241X |journal=Cretaceous Research |volume=128 |pages=104993 |doi=10.1016/j.cretres.2021.104993 |issn=0195-6671|url-access=subscription }}
- Genus †Primuluchara Wick, 2021 (Late Cretaceous of Alberta, Canada and Texas, US)
- Suborder Citharinoidei
- Genus †Eocitharinus Murray, 2002 (middle Eocene of Tanzania){{Cite journal |last=Murray |first=Alison M. |date=2003-09-12 |title=A new Eocene citharinoid fish (Ostariophysi: Characiformes) from Tanzania |url=https://www.tandfonline.com/doi/abs/10.1671/1854 |journal=Journal of Vertebrate Paleontology |volume=23 |issue=3 |pages=501–507 |doi=10.1671/1854 |issn=0272-4634|url-access=subscription }}
- Suborder Characoidei
- Genus †Tiupampichthys Gayet & Jegu, 2003 (latest Cretaceous to late Paleocene of Bolivia){{Cite journal |last=Gayet |first=Mireille |last2=Jégu |first2=Michel |last3=Bocquentin |first3=Jean |last4=Negri |first4=Francisco R. |date=2003-04-11 |title=New characoids from the Upper Cretaceous and Paleocene of Bolivia and the Mio-Pliocene of Brazil: phylogenetic position and paleobiogeographic implications |url=https://www.tandfonline.com/doi/abs/10.1671/0272-4634%282003%2923%5B28%3ANCFTUC%5D2.0.CO%3B2 |journal=Journal of Vertebrate Paleontology |volume=23 |issue=1 |pages=28–46 |doi=10.1671/0272-4634(2003)23[28:NCFTUC]2.0.CO;2 |issn=0272-4634|url-access=subscription }}
- Superfamily Characoidea{{Cite journal |last=Terán |first=Guillermo E |last2=Benitez |first2=Mauricio F |last3=Mirande |first3=J Marcos |date=2020-04-11 |title=Opening the Trojan horse: phylogeny of Astyanax, two new genera and resurrection of Psalidodon (Teleostei: Characidae) |url=https://doi.org/10.1093/zoolinnean/zlaa019 |journal=Zoological Journal of the Linnean Society |doi=10.1093/zoolinnean/zlaa019 |issn=0024-4082|url-access=subscription }}
- Genus †Bryconetes Weiss, Malabarba & Malabarba, 2014 (Late Eocene/Early Oligocene of Brazil){{Cite journal |last=Weiss |first=Fernanda E. |last2=Malabarba |first2=Maria Claudia |last3=Malabarba |first3=Luiz R. |date=2014 |title=A new stem fossil characid (Teleostei: Ostariophysi) from the Eocene-Oligocene of southeastern Brazil |url=https://www.scielo.br/j/ni/a/LvvWysnK97JkGWmjTynns5R/?format=html&lang=en&stop=next |journal=Neotropical Ichthyology |language=en |volume=12 |pages=439–450 |doi=10.1590/1982-0224-20140072 |issn=1679-6225}}
- Genus †Paleotetra Weiss, Malabarba & Malabarba, 2012 (Late Eocene/Early Oligocene of Brazil){{Cite journal |last=Weiss |first=Fernanda E. |last2=Malabarba |first2=Luiz R. |last3=Malabarba |first3=Maria Claudia |date=2012-03-01 |title=Phylogenetic relationships of Paleotetra, a new characiform fish (Ostariophysi) with two new species from the Eocene-Oligocene of south-eastern Brazil |url=https://www.tandfonline.com/doi/full/10.1080/14772019.2011.565082 |journal=Journal of Systematic Palaeontology |volume=10 |issue=1 |pages=73–86 |doi=10.1080/14772019.2011.565082 |issn=1477-2019|url-access=subscription }}
= Phylogeny =
Below is a phylogeny of living Characiformes based on Betancur-Rodriguez et al. 2017{{cite journal |journal=BMC Evolutionary Biology |volume=17 |issue=162 |title=Phylogenetic classification of bony fishes |first=Ricardo |last=Betancur-Rodriguez |author2=Edward O. Wiley |author3=Gloria Arratia |author4=Arturo Acero |author5=Nicolas Bailly |author6=Masaki Miya |author7=Guillaume Lecointre |author8=Guillermo Ortí |edition=4 |doi=10.1186/s12862-017-0958-3 |year=2017 |page=162 |pmc=5501477 |pmid=28683774 |doi-access=free |bibcode=2017BMCEE..17..162B }} and Nelson, Grande & Wilson 2016.{{cite book |publisher=John Wiley & Sons |title=Fishes of the World |first=Joseph S. |last=Nelson |author2=Terry C. Grande |author3=Mark V. H. Wilson |isbn=9781118342336 | edition=5th |year=2016}}
{{clade| style=font-size:100%;line-height:80%
|label1=Characiformes
|1={{clade
|label1=Citharinoidei
|1={{clade
|1=Distichodontidae Günther 1864 70 px
|2=Citharinidae Günther 1864 70 px
}}
|label2=Characoidei
|2={{clade
|label1=Crenuchales
|1=Crenuchidae Günther 1864 sensu Froese & Pauly 2001
|2={{clade
|label1=Erythrinales
|1={{clade
|label1=Alestioidea
|1={{clade
|1=Hepsetidae Hubbs 1939 70 px
|2=Alestiidae Cockerell 1910 70 px
}}
|2={{clade
|label1=Erythrinoidea
|1={{clade
|1=Tarumaniidae de Pinna et al. 2017
|2=Erythrinidae Valenciennes 1847 70 px
}}
|2={{clade
|label1=Serrasalmoidea
|label2=Anastomoidea
|1={{clade
|1=Serrasalmidae Bleeker 1859 70 px
|2={{clade
|1=Cynodontidae Eigenmann 1903 70 px
|2=Hemiodontidae Bleeker 1859 70 px
}}
}}
|2={{clade
|1=Parodontidae Eigenmann 1910
|2={{clade
|1={{clade
|1=Prochilodontidae Eigenmann 1909 70 px
|2={{clade
|1=Chilodidae Eigenmann 1903
|2=Curimatidae Gill 1858 70 px
}}
}}
|2=Anostomidae Günther 1864 sensu Nelson 1994 70 px
}}
}}
}}
}}
}}
|label2=Characales
|2={{clade
|label1=Lebiasinoidea
|1={{clade
|1=Ctenoluciidae Schultz 1944
|2=Lebiasinidae Gill 1889
}}
|2={{clade
|label1=Chalceoidea
|1=Chalceidae Fowler 1958
|2={{clade
|label1=Iguanodectoidea
|label2=Characoidea
|1={{clade
|1=Iguanodectidae Eigenmann 1909
|2=Acestrorhynchidae Eigenmann 1912
}}
|2={{clade
|1={{clade
|1=Triportheidae Fowler 1940 70 px
|2={{clade
|1=Bryconidae Eigenmann 1912 70 px
|2=Gasteropelecidae Bleeker 1859 70 px
}}
}}
|2=Characidae Latreille 1825 sensu Buckup 1998 70 px
}}
}}
}}
}}
}}
}}
}}
}}
Description
Characins possess a Weberian apparatus, a series of bony parts connecting the swim bladder and inner ear. Superficially, the Characiformes somewhat resemble their relatives of the order Cypriniformes, but have a small, fleshy adipose fin between the dorsal fin and tail. Most species have teeth within the mouth, since they are often carnivorous. The body is almost always covered in well-defined scales. The mouth is also usually not truly protractile.{{FishBase order | order = Characiformes | year = 2014|month=February}}
The largest characins are Hydrocynus goliath and Salminus franciscanus and Hoplias aimara,{{Cite web|url=http://www.fishing-worldrecords.com/scientificname/Salminus%20franciscanus/show|title=Fishing Worldrecords-characins-salminus franciscanus}} both of which are up to {{convert|1.2|m|ft|abbr=on}}. The smallest in size is about {{convert|1.7|cm|in|abbr=on}} in the Bolivian pygmy blue characin, Xenurobrycon polyancistrus.{{cite book |editor=Paxton, J.R. |editor2=Eschmeyer, W.N.|author1=Weitzman, S.H. |author2=Vari, R.P.|year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|pages= 101–105|isbn= 0-12-547665-5}} Many members are under {{convert|3|cm|in|abbr=on}}.
Distribution and habitat
Characins are most diverse in the Neotropics, where they are found in lakes and rivers throughout most of South and Central America. The red-bellied piranha, a member of the family Serrasalmidae within the Characiformes, is endemic to the Neotropical realm. At least 209 species of characins are found in Africa, including the distichodontids, citharinids, alestids, and hepsetids. The rest of the characins originate from the Americas.
Relationship to humans
A few characins become quite large, and are important as food or game. Most, however, are small shoaling fish. Many species commonly called tetras are popular in aquaria{{Cite journal |last1=Isbrücker |first1=I. J. H. |last2=Nijssen |first2=H. |date=1988 |title=Review of the South American characiform fish genus Chilodus, with description of a new species, C. gracilis (Pisces, Characiformes, Chilodontidae). |journal=Beaufortia |volume=38 |issue=3 |pages=47–56}} because of their bright colors, general hardiness, and tolerance towards other fish in community tanks.
References
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Category:Ray-finned fish orders
Category:Fish of South America
Category:Fish of Central America