Characiformes is an order of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, 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.; 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 Ostariophysi is the second-largest superorder of fish. Members of this superorder are called ostariophysians. This diverse group contains 10,758 species, about 28% of known fish species in the world and 68% of freshwater species, and are present ...

. The Otophysi contain three other orders,

Cypriniformes Cypriniformes is an order of ray-finned fish, which includes many families and genera of cyprinid ( carps and their kin) fish, such as barbs, loaches, botias, and minnows (among others). Cypriniformes is an "order-within-an-order", placed ...

, Siluriformes, and Gymnotiformes. The Characiformes form a group known as the Characiphysi with the Siluriformes and Gymnotiformes. The order Characiformes is the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

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 Characidae, the characids, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. They are found throughout much of Central and South America, including such major waterways as the Amazon and Orinoco Riv ...

. 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 In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

.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 Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

, about 270

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

, and at least 1674

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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. This group has a very ancient divergence from the rest of the Characiformes, dating back to the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

or earlier, and it has been suggested that it be better treated as its own order, the Cithariniformes.

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 The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

Fossils

The earliest characiform fossils date back to the Late Cretaceous, around the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

. Other fossil teeth date back to the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

, 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 The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

(

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

Age) of

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. This presumably marine taxon was used as evidence of characiformes potentially having marine origins. 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. 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 The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

of France, which have a large, multi-cusped appearance reminiscent of African alestids. Similarly, two

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

freshwater characiform genera, '' Primuluchara'' and '' Eotexachara'', are known from North America, with ''Primuluchara'' having a very wide distribution across

Laramidia Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Year#SI prefix multipliers, Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island ...

, ranging from Texas to as far north as southern Canada (

Dinosaur Park Formation The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 7 ...

). 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. 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,

, and

Serrasalmidae The Serrasalmidae (serrasalmids) are a family of characiform fishes native to freshwater habitats of South America. They include more than 90 species. The name means "serrated salmon family", which refers to the serrated keel running along the ...

. Characins appear to have inhabited Europe into the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

, with fossil teeth reminiscent of '' Alestes'' known from the

Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

of Spain. '' Eurocharax'' Gaudant, 1980 is known from a fully-articulated specimen from the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

of France, and appears to represent an estuarine taxon, although its phylogenetic position needs revision. 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''.

Taxonomy

The following classification is based on ''

Eschmeyer's Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously up ...

'' (2025). Betancur ''et al'' (2018) & Melo ''et al'' (2022) recognise some supra-familial divisions but these are not recognised by ''Eschmeyer's Catalog of Fishes'' * Order Characiformes ** Suborder Citharinoidei *** Family Citharinidae Günther, 1864 (citharinids) *** Family Distichodontidae Günther, 1864 (distichodontids) ** Suborder Characoidei *** Family Crenuchidae Günther 1864 (crenuchids) *** Family Alestidae Cockerell, 1910 (African tetras) *** Family Lepidarchidae Melo & Stiassny, 2024 *** Family Hepsetidae Hubbs, 1939 (African pikes) *** Family Tarumaniidae de Pinna, Zuanon, Rapp Py-Daniel & Petry, 2017 (muckfishes) *** Family Erythrinidae

Valenciennes Valenciennes (, also , , ; ; or ; ) is a communes of France, commune in the Nord (French department), Nord Departments of France, department, Hauts-de-France, France. It lies on the Scheldt () river. Although the city and region experienced ...

, 1847 (trahiras) *** Family Parodontidae Eigenmann, 1910 (darter tetras) *** Family Cynodontidae Eigenmann, 1903 (sabertoothed characids) *** Family

Bleeker, 1859 (piranhas and allies) *** Family Hemiodontidae Bleeker, 1859 (hemiodontids) *** Family Anostomidae Günther, 1864 (toothed headstanders) *** Family Chilodidae Eigenmann, 1910 (headstanders) *** Family Curimatidae

Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

, 1858 (toothless characiforms) *** Family

Prochilodontidae The Prochilodontidae, or flannel-mouthed characins, are a small family of freshwater fishes found primarily in the northern half of South America, south to Paraguay and northern Argentina. This family is closely related to the Curimatidae, and in ...

Eigenmann, 1909 (bocachicos) *** Family

Lebiasinidae The Lebiasinidae are a family (biology), family of freshwater fishes found in Costa Rica, Panama, and South America. They are usually small and are known as ornamental fishes in Aquarium, aquaria, including popular fishes such as the various penc ...

Gill, 1889 (lebiasinids) *** Family

Ctenoluciidae The Ctenoluciidae (meaning "comb light family"), also known as pike-characins, are a small family of freshwater fishes from Panama and South America. They have elongated, Esox, pike-like bodies, and several sharp and conical teeth. They are rela ...

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 Stevardiidae is a large family of freshwater fish in the order Characiformes. It includes many genera previously placed in the family Characidae, which was split into multiple families in 2024. They are found throughout South and Central Americ ...

Gill, 1858 (stevardiids) *** Family

Latreille, 1825 (characids) *** Family Acestrorhamphidae Eigenmann, 1907 (American tetras) ****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 The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

of Texas, US) ** Genus †'' Primuluchara'' Wick, 2021 (Late Cretaceous of Alberta, Canada and Texas, US)'''' ** Suborder Citharinoidei *** Genus †'' Eocitharinus'' Murray, 2002 (

middle Eocene The Eocene ( ) is a geological epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', ' Dawn') a ...

of Tanzania) ** Suborder Characoidei *** Genus †'' Tiupampichthys'' Gayet & Jegu, 2003 (latest Cretaceous to

late Paleocene The Thanetian is, in the International Commission on Stratigraphy, ICS Geologic timescale, the latest age (geology), age or uppermost stage (stratigraphy), stratigraphic stage of the Paleocene epoch (geology), Epoch or series (stratigraphy), Serie ...

of Bolivia) *** Superfamily Characoidea **** Genus †'' Bryconetes'' Weiss, Malabarba & Malabarba, 2014 (

Late Eocene The Priabonian is, in the International Commission on Stratigraphy, ICS's geologic timescale, the latest age (geology), age or the upper stage (stratigraphy), stage of the Eocene epoch (geology), Epoch or series (stratigraphy), Series. It spans ...

Early Oligocene The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

of Brazil) **** Genus †'' Paleotetra'' Weiss, Malabarba & Malabarba, 2012 (Late Eocene/Early Oligocene of Brazil)

Phylogeny

Below is a phylogeny of living Characiformes based on Betancur-Rodriguez ''et al.'' 2017 and Nelson, Grande & Wilson 2016.

Description

Characins possess a Weberian apparatus, a series of bony parts connecting the

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

and

inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...

. Superficially, the Characiformes somewhat resemble their relatives of the order

, but have a small, fleshy

adipose fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only b ...

between the

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

and

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

. Most species have teeth within the mouth, since they are often

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

. The body is almost always covered in well-defined scales. The mouth is also usually not truly protractile. The largest characins are '' Hydrocynus goliath'' and '' Salminus franciscanus'' and '' Hoplias aimara'', both of which are up to . The smallest in size is about in the Bolivian pygmy blue characin, '' Xenurobrycon polyancistrus''. Many members are under .

Distribution and habitat

Characins are most diverse in the

Neotropics The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeog ...

, where they are found in lakes and rivers throughout most of

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

and

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

. The

red-bellied piranha The red-bellied piranha, also known as the red piranha (''Pygocentrus nattereri''), is a Type (biology), type of piranha native to South America, found in the Amazon basin, Amazon, Paraguay River, Paraguay, Paraná River, Paraná and Essequibo Ri ...

, a member of the family

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 The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

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 because of their bright colors, general hardiness, and tolerance towards other fish in community tanks.

References

{{Authority control Ostariophysi Ray-finned fish orders Fish of Africa Fish of South America Fish of Central America Extant Santonian first appearances Taxa named by Charles Tate Regan