Characidae, the characids or characins is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does inclu ...

subtropical The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north and ...

and

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

, belonging to the order

Characiformes Characiformes 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.; Buckup P.A.: "Relationshi ...

. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their status as a by and large

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

group at family rank. To arrive there, this family has undergone much systematic and taxonomic change. Among those fishes that remain in the Characidae for the time being are the

tetra Terrestrial Trunked Radio (TETRA; formerly known as Trans-European Trunked Radio), a European standard for a trunked radio system, is a professional mobile radio and two-way transceiver specification. TETRA was specifically designed for use by go ...

s, comprising the very similar genera ''

Hemigrammus ''Hemigrammus'' is a genus of freshwater fish in the family Characidae native to South America (including Trinidad) and commonly seen in the aquarium trade. These are medium-small tetras where the largest species reach up to around . Species Th ...

'' and ''

Hyphessobrycon ''Hyphessobrycon'' is a genus of freshwater fish in the family Characidae. These species are among the fishes known as tetras. The genus is distributed in the Neotropical realm from southern Mexico to Río de la Plata in Argentina. Many of these ...

'', as well as a few related forms such as the

cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as se ...

and

neon Neon is a chemical element with the symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. It was discovered (along with krypton ...

tetras. Fish of this family are important as food and also include popular

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

fish species. These fish vary in length, though many are less than . One of the smallest species, ''Hyphessobrycon roseus'', grows to a maximum length of 1.9 cm. These fish inhabit a wide range and a variety of habitats. They originate in the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with t ...

, ranging from southwestern

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by b ...

and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

through Central and South America.Nelson (2006) Many of these fish come from rivers, but, for example, the blind cave tetra even inhabits

Systematics

This family has undergone a large amount of systematic and

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. A ...

change. More recent revision has moved many former members of the family into their own related but distinct families – the pencilfishes of the genus '' Nannostomus'' are a typical example, having now been moved into the Lebiasinidae, the assorted predatory species belonging to '' Hoplias'' and '' Hoplerythrinus'' have now been moved into the Erythrinidae, and the sabre-toothed fishes of the genus '' Hydrolycus'' have been moved into the Cynodontidae. The former subfamily Alestiinae was promoted to family level ( Alestiidae) and the subfamilies Crenuchinae and Characidiinae were moved to the family Crenuchidae. Myleus_schomburgkii

Other fish families that were formerly classified as members of the Characidae, but which were moved into separate families of their own during recent taxonomic revisions (after 1994) include Acestrorhynchidae, Anostomidae, Chilodontidae, Citharinidae, Ctenoluciidae, Curimatidae, Distichodontidae, Gasteropelecidae, Hemiodontidae, Hepsetidae, Parodontidae, Prochilodontidae, Serrasalmidae, and Triportheidae.Oliveira, C., Avelino, G.S., Abe, K.T., Mariguela, T.C., Benine, R.C., Orti, G., Vari, R.P., & Correa e Castro, R.M. (2011)
Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling.
''BMC Evolutionary Biology, 11: 275. doi: 10.1186/1471-2148-11-275'' The larger

piranha A piranha or piraña (, , or ; or , ) is one of a number of freshwater fish in the family Serrasalmidae, or the subfamily Serrasalminae within the tetra family, Characidae in order Characiformes. These fish inhabit South American rivers, ...

s were originally classified as belonging to the Characidae, but various revisions place them in their own related family, the Serrasalmidae. This reassignment has yet to enjoy universal acceptance, but is gaining in popularity among taxonomists working with these fishes. Given the current state of flux of the Characidae, a number of other changes will doubtless take place, reassigning once-familiar species to other families. Indeed, the entire

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

of the

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 ...

– fishes possessing a

Weberian apparatus The Weberian apparatus is an anatomical structure that connects the swim bladder to the auditory system in fishes belonging to the superorder Ostariophysi. When it is fully developed in adult fish, the elements of the apparatus are sometimes col ...

– has yet to be settled conclusively. Until that phylogeny is settled, the opportunity for yet more upheavals within the taxonomy of the characoid fishes is considerable.

Classification

Phylogeny

Hyphessobrycon pyrrhonotus thomnight 001

Taxonomy

The subfamilies and tribes currently recognized by most if not all authors, and their respective genera, are:

Subfamily ''Spintherobolus'' clade * '' Amazonspinther'' * '' Spintherobolus'' Subfamily '' Stethaprioninae'' * Tribe Rhoadsiini 'Astyanax'' clade** '' Astyanacinus'' ** ''

Astyanax In Greek mythology, Astyanax (; grc, Ἀστυάναξ ''Astyánax'', "lord of the city") was the son of Hector, the crown prince of Troy, and his wife, Princess Andromache of Cilician Thebe."Astyanax". ''Oxford Classical Dictionary''. Oxford, 1 ...

'' ** '' Carlana'' ** '' Ctenobrycon'' ** '' Inpaichthys'' ** '' Nematobrycon'' ** '' Oligosarcus'' ** '' Parastremma'' ** '' Psellogrammus'' ** '' Rhoadsia'' * Tribe Stygichthyini 'Jupiaba'' clade** '' Coptobrycon'' ** '' Deuterodon'' ** '' Erythrocharax''Netto-Ferreira, A.L., Birindelli, J.L.O., de Sousa, L.M., Mariguela, T.C. & Oliveira, C. (2013)
A New Miniature Characid (Ostariophysi: Characiformes: Characidae), with Phylogenetic Position Inferred from Morphological and Molecular Data.
''PLoS ONE, 8 (1): e52098. doi:10.1371/journal.pone.0052098'' ** '' Jupiaba'' ** '' Macropsobrycon'' ** '' Myxiops'' ** '' Parecbasis'' ** '' Probolodus'' ** '' Stygichthys'' * Tribe Pristellini 'Hemigrammus'' clade; Aphyoditini** '' Aphyodite'' ** '' Atopomesus'' ** '' Axelrodia'' ** '' Brittanichthys'' ** '' Bryconella'' ** '' Hasemania'' ** ''

'' ** ''

'' ** '' Moenkhausia'' ** '' Nematocharax'' ** '' Paracheirodon'' ** '' Parapristella'' ** '' Petitella'' ** '' Phycocharax''Ohara, W.M., Mirande, J.M. & Lima, F.C.T.d. (2017)
''Phycocharax rasbora'', a new genus and species of Brazilian tetra (Characiformes: Characidae) from Serra do Cachimbo, rio Tapajós basin.
''PLoS ONE, 12 (2): e0170648.'' ** '' Pristella'' ** '' Thayeria'' * Tribe Stethaprionini ** '' Brachychalcinus'' ** '' Gymnocorymbus'' ** '' Orthospinus'' ** '' Poptella'' ** '' Stethaprion'' ** '' Stichonodon'' * Tribe Gymnocharacini ** ''

Bario Bario is a community of 13 to 16 villages located on the Kelabit Highlands in Miri Division, Sarawak, Malaysia, lying at an altitude of 1000 m (3280 ft) above sea level. It is located close to the Sarawak-Kalimantan border, 178 k ...

'' ** '' Dectobrycon'' ** '' Ectrepopterus'' ** '' Grundulus'' ** '' Gymnocharacinus'' ** '' Gymnotichthys'' ** '' Hollandichthys'' ** '' Pseudochalceus'' ** '' Rachoviscus'' ** '' Schultzites'' * Tribe Scissorini ** '' Genycharax'' ** '' Leptobrycon'' ** '' Microschemobrycon'' ** '' Mixobrycon'' ** '' Oligobrycon'' ** '' Oxybrycon'' ** '' Scissor'' ** '' Serrabrycon'' ** '' Thrissobrycon'' ** '' Tucanoichthys'' ** '' Tyttobrycon'' Subfamily Stevardiinae * Tribe Eretmobryconini ** '' Eretmobrycon'' ** '' Markiana'' * Tribe Xenurobryconini ** '' Iotabrycon'' ** '' Ptychocharax'' ** '' Scopaeocharax'' ** '' Tyttocharax'' ** '' Xenurobrycon'' * Tribe ''Argopleura'' clade ** '' Argopleura'' * Tribe Glandulocaudini ** '' Glandulocauda'' ** '' Lophiobrycon'' ** '' Mimagoniates'' * Tribe Stevardiini ** '' Chrysobrycon'' ** '' Corynopoma'' ** '' Gephyrocharax'' ** '' Hysteronotus'' ** '' Pseudocorynopoma'' ** '' Pterobrycon'' * Tribe Hemibryconini ** '' Acrobrycon'' ** '' Hemibrycon'' 'Boehlkea''.html"_;"title="Boehlkea.html"_;"title="'Boehlkea">'Boehlkea''">Boehlkea.html"_;"title="'Boehlkea">'Boehlkea''*_Tribe_Creagrutini.html" ;"title="Boehlkea">'Boehlkea''.html" ;"title="Boehlkea.html" ;"title="'Boehlkea">'Boehlkea''">Boehlkea.html" ;"title="'Boehlkea">'Boehlkea''* Tribe Creagrutini">Boehlkea">'Boehlkea''.html" ;"title="Boehlkea.html" ;"title="'Boehlkea">'Boehlkea''">Boehlkea.html" ;"title="'Boehlkea">'Boehlkea''* Tribe Creagrutini ** ''Carlastyanax'' ** ''Creagrutus'' * Tribe Landonini ** ''Landonia'' * Tribe Phenacobryconini ** ''Phenacobrycon'' * Tribe Trochilocharacini ** ''Trochilocharax'' * Tribe Diapomini ** '' Attonitus'' ** '' Aulixidens'' ** '' Bryconacidnus'' ** '' Bryconamericus'' 'Hypobrycon''.html"_;"title="Hypobrycon.html"_;"title="'Hypobrycon">'Hypobrycon''">Hypobrycon.html"_;"title="'Hypobrycon">'Hypobrycon''**_''Caiapobrycon.html" ;"title="Hypobrycon">'Hypobrycon''.html" ;"title="Hypobrycon.html" ;"title="'Hypobrycon">'Hypobrycon''">Hypobrycon.html" ;"title="'Hypobrycon">'Hypobrycon''** ''Caiapobrycon">Hypobrycon">'Hypobrycon''.html" ;"title="Hypobrycon.html" ;"title="'Hypobrycon">'Hypobrycon''">Hypobrycon.html" ;"title="'Hypobrycon">'Hypobrycon''** ''Caiapobrycon'' ** ''Ceratobranchia'' ** ''Cyanogaster''Mattox, G.M.T., Britz, R., Toledo-Piza, M. & Marinho, M.M.F. (2013): Cyanogaster noctivaga, a remarkable new genus and species of miniature fish from the Rio Negro, Amazon basin (Ostariophysi: Characidae). ''Ichthyological Exploration of Freshwaters, 23 (4): 297-318.'' ** '' Diapoma'' ** '' Knodus'' ** '' Lepidocharax'' ** '' Microgenys'' ** '' Monotocheirodon'' ** '' Othonocheirodus'' ** '' Phallobrycon'' ** '' Piabarchus'' ** '' Piabina'' ** '' Planaltina'' ** '' Rhinobrycon'' ** '' Rhinopetitia'' Subfamily Characinae * Tribe Protocheirodontini ** '' Protocheirodon''Vari, R.P., Melo, B.F. & Oliveira, C. (2016): ''Protocheirodon'', a new genus of Characidae (Teleostei: Characiformes) with the redescription of the poorly known ''Protocheirodon pi''. ''Neotropical Ichthyology, 14 (2): e150154.'' * Tribe Pseudocheirodontini ** '' Nanocheirodon'' ** '' Pseudocheirodon'' * Tribe Aphyocharacini ** '' Aphyocharacidium'' ** '' Aphyocharax'' ** '' Leptagoniates'' ** '' Paragoniates'' ** '' Phenagoniates'' ** '' Prionobrama'' ** '' Xenagoniates'' * Tribe Cheirodontini ** '' Cheirodon'' ** '' Heterocheirodon'' ** '' Prodontocharax'' ** '' Saccoderma'' * Tribe Compsurini ** '' Acinocheirodon'' ** '' Compsura'' ** '' Ctenocheirodon''Malabarba, L.R. & Jerep, F.C. (2012): A New Genus and Species of Cheirodontine Fish from South America (Teleostei: Characidae). ''Copeia, 2012 (2): 243-250.'' ** '' Holoshesthes'' 'Aphyocheirodon'';_''Cheirodontops.html" ;"title="Aphyocheirodon.html" ;"title="'Aphyocheirodon">'Aphyocheirodon''; ''Cheirodontops">Aphyocheirodon.html" ;"title="'Aphyocheirodon">'Aphyocheirodon''; ''Cheirodontops''] ** ''Kolpotocheirodon'' ** ''Odontostilbe'' ** ''Serrapinnus'' * Tribe Exodontini ** ''Bryconexodon'' ** ''Bucktooth tetra, Exodon'' ** ''Roeboexodon'' * Tribe [ etragonopterinae ** '' Tetragonopterus'' * Tribe Characini ** '' Acanthocharax'' ** '' Acestrocephalus'' ** '' Charax'' ** '' Cynopotamus'' ** '' Galeocharax'' ** '' Phenacogaster'' ** '' Priocharax'' ** '' Roeboides''

Former members

The Chalceidae, Iguanodectidae, Bryconidae and Heterocharacinae are the most recent clades to be removed in order to maintain a monophyletic Characidae.

Subfamily Iguanodectinae moved to Iguanodectidae * '' Bryconops'' * '' Iguanodectes'' * '' Piabucus'' Subfamily Heterocharacinae moved to Acestrorhynchidae * '' Gnathocharax'' * '' Heterocharax'' * '' Hoplocharax'' * '' Lonchogenys'' Subfamily Bryconinae moved to Bryconidae * '' Brycon'' * '' Chilobrycon'' * '' Henochilus'' Subfamily Salmininae moved to Bryconidae * '' Salminus'' Genera incertae sedis * '' Chalceus'' moved to Chalceidae

Genera ''incertae sedis''

A large number of

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

in this family are ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertaint ...

''. The relationships of many fish in this family – in particular species traditionally placed in the etragonopterinae,_which_had_become_something_of_a_"

etragonopterinae,_which_had_become_something_of_a_"wastebin_taxon">etragonopterinae,_which_had_become_something_of_a_"wastebin_taxon"_–_are_poorly_known,_a_comprehensive_phylogenetic_study_for_the_entire_family_is_needed._The_genera_''Hyphessobrycon_ ''Hyphessobrycon''_is_a_genus_of_freshwater_fish_in_the_family_Characidae._These_species_are_among_the_fishes_known_as_tetras._The_genus_is_distributed_in_the_Neotropical_realm_from_southern_Mexico_to_Río_de_la_Plata_in_Argentina._Many_of_these__...

'',_''Astyanax_ In_Greek_mythology,_Astyanax_(;__grc,_Ἀστυάναξ_''Astyánax'',_"lord_of_the_city")_was_the_son_of_Hector,_the_crown_prince_of_Troy,_and_his_wife,_Princess_Andromache_of_Cilician_Thebe."Astyanax"._''Oxford_Classical_Dictionary''._Oxford,_1_...