View source for Cyprinodontiformes

{{Short description|Order of fishes}}
{{Automatic taxobox
| fossil_range = {{Fossil range|Late Paleocene|recent}}<!-- Encyclopedia of Fishes -->
| image = Mummichog.jpg
| image_upright = 1.15
| image_caption = [[Mummichog]] (''Fundulus heteroclitus heteroclitus'')<br/>Female (top right) and two males
| taxon = Cyprinodontiformes
| authority = [[Leo S. Berg|L. S. Berg]], 1940
| subdivision_ranks = Suborders
| subdivision = [[Aplocheiloidei]]<br />
[[Cyprinodontoidei]]
| synonyms = Microcyprini <small>Regan, 1909</small>
| type_species = ''[[Cyprinodon variegatus]]''
| type_species_authority = Lacépède, 1803
}}

'''Cyprinodontiformes''' {{IPAc-en|ˌ|s|ɪ|p|r|ᵻ|n|oʊ-|ˈ|d|ɒ|n|t|ᵻ|f|ɔːr|m|iː|z}} is an [[order (biology)|order]] of [[Actinopterygii|ray-finned fish]], comprising mostly small, freshwater fish.<ref>{{FishBase order | order = Cyprinodontiformes | month = August | year = 2007}}</ref>  Many popular aquarium fish, such as [[killifish]] and [[Poeciliidae|live-bearers]], are included.  They are closely related to the [[Atheriniformes]] and are occasionally included with them.  A colloquial term for the order as a whole is '''toothcarps''', though they are not actually close relatives of the true [[carp]]s &ndash; the latter belong to the [[superorder]] [[Ostariophysi]], while the toothcarps are [[Acanthopterygii]].

The families of Cyprinodontiformes can be informally divided into three groups based on reproductive strategy: [[Viviparity|viviparous]] and [[Ovoviviparity|ovoviviparous]] (all species give live birth), and [[Oviparity|oviparous]] (all species are egg-laying). The live-bearing groups differ in whether the young are carried to term within (ovoviviparous) or without (viviparous) an enclosing eggshell. [[Phylogeny|Phylogenetically]] however, one of the two [[suborders]] &ndash; the [[Aplocheiloidei]] &ndash; contains oviparous species exclusively, as do two of the four [[Superfamily (zoology)|superfamilies]] of the other suborder (the [[Cyprinodontoidea]] and [[Valencioidea]] of the [[Cyprinodontoidei]]). Vivipary and ovovivipary have [[Evolution|evolved]] independently from oviparous ancestors, the latter possibly twice.

The oldest fossil record of the group is the extinct ?''Cyprinodon primulus'', a ''[[nomen vanum]]'' known from isolated fossil scales from the [[Late Paleocene]] of Argentina. Its exact taxonomic identity is uncertain, although it is generally considered to at least be a true cyprinodontiform.<ref>{{Cite journal |last1=Altner |first1=Melanie |last2=Reichenbacher |first2=Bettina |date=2015-04-29 |title=†Kenyaichthyidae fam. nov. and †Kenyaichthys gen. nov. – First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes) |journal=PLOS ONE |language=en |volume=10 |issue=4 |article-number=e0123056 |doi=10.1371/journal.pone.0123056 |doi-access=free |issn=1932-6203 |pmc=4414574 |pmid=25923654|bibcode=2015PLoSO..1023056A }}</ref><ref>{{Cite journal |last1=Bogan |first1=Sergio |last2=Contreras |first2=Víctor H. |last3=Agnolin |first3=Federico |last4=Tomassini |first4=Rodrigo L. |last5=Peralta |first5=Silvio |date=2018-12-01 |title=New genus and species of Anablepidae (Teleostei, Cyprinodontiformes) from the Late Miocene of Argentina |url=https://www.sciencedirect.com/science/article/abs/pii/S089598111830258X |journal=Journal of South American Earth Sciences |volume=88 |pages=374–384 |doi=10.1016/j.jsames.2018.09.009 |bibcode=2018JSAES..88..374B |issn=0895-9811|url-access=subscription }}</ref>

==Description==
[[Image:Fundulopanchax scheeli.png|thumb|left|''[[Fundulopanchax scheeli]]'', a killifish of the family [[Nothobranchiidae]].]]
Some members of this order are notable for inhabiting extreme environments, such as [[saline water|saline]] or very warm waters, heavily polluted waters, rain water pools devoid of minerals and made acidic by decaying vegetation, or isolated situations where no other types of fish occur.

They are typically [[carnivore]]s, and often live near the surface, where the oxygen-rich water compensates for environmental disadvantages. Scheel (1968) observed the gut contents were invariably ants, others have reported insects, worms and aquatic crustaceans. Aquarium specimens are invariably seen eating protozoans from the water column and the surfaces of leaves, however these are not apparent as stomach contents. Many members of the family [[Cyprinodontidae]] (the pupfishes) eat plant material as well and some have adapted to a diet very high in algae to the point where one, the [[Flagfish]] also known as American flagfish, is a renowned algae eater in the aquarium, in spite of belonging to an order of fishes that do not generally consume any plant material. In addition, killifish derive some of the [[carotenoids]] and other chemicals required to make their body pigments from pollen grains on the surface of and in the gut of insects they eat from the surface of the water; this can be simulated in culture by the use of special color enhancing foods that contain these compounds.

Although the Cyprinodontiformes are a diverse group, most species contained within are small to medium-sized fish, with small mouths, large eyes, a single [[dorsal fin]], and a rounded [[caudal fin]]. The largest species is the ''cuatro ojos'' (''[[Anableps dowei]]''), which measures {{convert|34|cm|in|abbr=on}}<ref>{{cite web| url = http://www.discoverlife.org/mp/20q?search=Anableps+dowi&flags=col3:&res=320| archive-url = https://web.archive.org/web/20110612034131/http://www.discoverlife.org/mp/20q?search=Anableps+dowi&flags=col3:&res=320| archive-date = 2011-06-12| title = Anableps dowi - Pacific Foureyed Fish -- Discover Life}}</ref> in length, while the smallest, the least killifish (''[[Heterandria formosa]]''), is just {{convert|8|mm|in|abbr=on}} long as an adult.<ref name=EoF>{{cite book |editor1=Paxton, J.R. |editor2=Eschmeyer, W.N. |author= Parenti, Lynne R.|year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|pages= 148–151|isbn= 0-12-547665-5}}</ref>

==Systematics==
Based on ''[[Eschmeyer's Catalog of Fishes]]'' (2025):<ref name=":1">{{Cite web |last1=Fricke |first1=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}}</ref>[[Image:Guppy-male.jpg|thumb|right|[[Guppy]], a live-bearer of the [[Poeciliidae]]]]
'''CYPRINODONTIFORMES'''
* Suborder [[Aplocheiloidei]] (all oviparous)
** Family [[Aplocheilidae]] - Asian killifishes
** Family [[Nothobranchiidae]] - African killifishes
** Family †[[Kenyaichthyidae]] (Miocene of Kenya)<ref name=":0">{{Cite journal |last1=Altner |first1=Melanie |last2=Reichenbacher |first2=Bettina |date=2015-04-29 |title=†Kenyaichthyidae fam. nov. and †Kenyaichthys gen. nov. – First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes) |journal=PLOS ONE |language=en |volume=10 |issue=4 |article-number=e0123056 |bibcode=2015PLoSO..1023056A |doi=10.1371/journal.pone.0123056 |issn=1932-6203 |pmc=4414574 |pmid=25923654 |doi-access=free}}</ref>
** Family [[Rivulidae]] - New World killifishes
* Suborder [[Cyprinodontoidei]]
** Family [[Pantanodontidae]] - spine killifishes (oviparous)
** Family [[Fundulidae]] - topminnows (oviparous)
** Family [[Cyprinodontidae]] - pupfishes (oviparous)
** Family [[Profundulidae]] - Middle American killifishes (oviparous)
** Family [[Goodeidae]] - splitfins or goodeids (largely viviparous)
** Family [[Fluviphylacidae]] - American lampeyes (oviparous)
** Family [[Anablepidae]] - four-eyed fish (largely ovoviviparous)
** Family [[Poecilidae]] - livebearers (viviparous)
** Family [[Aphaniidae]] - Oriental killifishes (oviparous)
** Family [[Valenciidae]] - Valencia toothcarps (oviparous)
** Family [[Procatopodinae|Procatopodidae]] - African lampeyes (oviparous)

The family Aplocheilidae has been expanded by some authorities to include all the killifishes with three subfamilies, Aplocheilinae, Cynolebiinae and Nothobranchiinae,<ref name=Costa2016>{{cite journal | author = Costa, W.J.E.M. | year = 2016 | url = http://www.senckenberg.de/files/content/forschung/publikationen/vertebratezoology/vz66-2/03_vertebrate_zoology_66-2_costa_125-140.pdf | title = Comparative morphology and classification of South American cynopoeciline killifishes (Cyprinodontiformes: Aplocheilidae), with notes on family-group names used for aplocheiloids.  | journal =Vertebrate Zoology | volume = 66 | issue = 2 | pages = 125–140| doi = 10.3897/vz.66.e31538 | doi-access = free }}</ref> but this is not the classification adopted in the 5th Edition of ''[[Fishes of the World]]''.<ref name = Nelson5>{{cite book |title=Fishes of the World |edition=5th |author1=J. S. Nelson |author2=T. C. Grande |author3=M. V. H. Wilson |year=2016 |page=371 |publisher=Wiley |isbn=978-1-118-34233-6 |url=https://sites.google.com/site/fotw5th/ |access-date=2019-08-25 |archive-date=2019-04-08 |archive-url=https://web.archive.org/web/20190408194051/https://sites.google.com/site/fotw5th/ }}</ref>

=== Phylogeny ===
Based on:<ref name=":0" /><ref name=":02">{{Cite journal |last1=Bragança |first1=Pedro H. N. |last2=Amorim |first2=Pedro F. |last3=Costa |first3=Wilson J. E. M. |date=2018-02-09 |title=Pantanodontidae (Teleostei, Cyprinodontiformes), the sister group to all other cyprinodontoid killifishes as inferred by molecular data |url=https://zse.pensoft.net/articles.php?id=22173 |journal=Zoosystematics and Evolution |language=en |volume=94 |issue=1 |pages=137–145 |doi=10.3897/zse.94.22173 |issn=1860-0743 |doi-access=free}}</ref>{{Clade
|label1='''Cyprinodontiformes'''
|1={{clade
 |label1=[[Aplocheiloidei]]
 |1={{clade
 |1=[[Aplocheilidae]]
 |2={{clade
   |1=[[Nothobranchiidae]]
   |2=[[Rivulidae]]
   |3={{extinct}}[[Kenyaichthyidae]]
    }}
 }}
  |label2=[[Cyprinodontoidei]]
  |2={{clade
     |1=[[Pantanodontidae]]
     |2={{clade
       |1=[[Cyprinodontidae]]
       |2={{clade
          |1={{clade
            |1=[[Profundulidae]]
            |2=[[Goodeidae]]
          }}
          |2={{clade
             |1=[[Fundulidae]]
             |2={{clade
               |1={{clade
                  |1=[[Fluviphylacidae]] 
                  |2={{clade
                     |1=[[Anablepidae]]
                     |2=[[Poecilidae]]
                  }}
               }}
               |2={{clade
                 |1=[[Procatopodidae]]
                 |2={{clade
                    |1=[[Aphaniidae]]
                    |2=[[Valenciidae]]
                 }}
              }}
        }}
       }}
      }}
   }}
}}
}}
}}

==References==
{{Commons category}}
{{Reflist}}

{{Actinopterygii}}
{{Taxonbar|from=Q143748}}
{{Authority control}}

[[Category:Cyprinodontiformes| ]]
[[Category:Extant Oligocene first appearances]]
[[Category:Ray-finned fish orders]]