{{Short description|Family of fish}} {{Distinguish|Iguanodontidae}}
{{Automatic taxobox | taxon = Iguanodectidae | authority = C. H. Eigenmann, 1909<ref name = VDLEF>{{cite journal | author1 = Richard van der Laan | author2 = William N. Eschmeyer | author3 = Ronald Fricke | name-list-style = amp |year=2014 | title = Family-group names of recent fishes | url = https://biotaxa.org/Zootaxa/article/view/zootaxa.3882.1.1/10480 | journal = Zootaxa | volume = 3882 | issue = 2 | pages = 1–230| doi = 10.11646/zootaxa.3882.1.1 | pmid = 25543675 | doi-access = free }}</ref> | subdivision_ranks = Genera | subdivision = see text | image = Iguanodectes geisleri - AquaPorteDoree.JPG | image_caption = ''Iguanodectes geisleri'' }}
'''Iguanodectidae''' is a family of freshwater fish in the order Characiformes that lives in South America. It contains three genera: ''Iguanodectes, Piabucus'', and ''Bryconops''. Several species in the family, such as the green line lizard tetra (''Iguanodectes spilurus''), the tailspot tetra (''Bryconops caudomaculatus''), and the orangefin tetra (''Bryconops affinis''), are sometimes taken as aquarium fish.
== Etymology == [[File:Bryconops cf caudomaculatus.jpg|left|thumb|''Bryconops'' cf. ''caudomaculatus'']]
The family name "Iguanodectidae" originates in the genus name "''Iguanodectes''", which used to be its sole representative.<ref name=":1" /> The origin of such was not made clear upon its nomination, but is assumed to be from "iguana", the lizard, and "dectes", meaning "bite", in reference to the general dentition's almost lizard-like formation.<ref name="ETYFish">{{cite web |author=Christopher Scharpf |date=3 January 2024 |title=Family IGUANODECTIDAE Eigenmann 1909 [no common name] |url=https://etyfish.org/iguanodectidae/ |access-date=21 August 2025 |work=The ETYFish Project Fish Name Etymology Database |publisher=Christopher Scharpf}}</ref> The common name "lizard bite tetra" has been proposed in reference to this, though this has not been widely accepted as of 2022.<ref name="FishBase" /><ref>{{Cite web |title=Iguanodectidae names - Encyclopedia of Life |url=https://eol.org/pages/46581541/names |access-date=2022-02-03 |website=eol.org}}</ref>
== Description == thumb|An 1800s-era illustration of ''Piabuca argentina'', now named ''Piabucus dentatus''
Iguanodectids are generally small, and are brightly colored or reflective, making them moderately-popular ornamental fish. They range from 3.1 cm to 15 cm SL (standard length).<ref name="FishBaseBryconops">{{FishBase genus|genus=Bryconops|month=February|year=2022}}</ref><ref name="FishBaseIguanodectes">{{FishBase genus|genus=Iguanodectes|month=February|year=2022}}</ref><ref name="FishBasePiabucus">{{FishBase genus|genus=Piabucus|month=February|year=2022}}</ref> They are rather narrow in shape, somewhat resembling minnows; ichthyologist Carl H. Eigenmann compared them to smelt.<ref name="AmericanCharacidae">{{cite book|last1=Eigenmann|first1=Carl H.|url=https://www.biodiversitylibrary.org/page/4372702|title=The American Characidae|last2=Meyers|first2=George S.|date=1917–1929|publisher=Cambridge|pages=493–494|access-date=3 February 2022}}</ref>
Members of ''Piabucus'' are slightly larger than members of ''Iguanodectes'', reaching a maximum of 12.9 cm (5.1 in), while members of ''Iguanodectes'' only reach 10.3 cm (4.1 in).<ref name="FishBasePiabucus"/><ref name="FishBaseIguanodectes"/> They are slender and rather elongate in body shape, comparable to minnows; ichthyologist Carl H. Eigenmann, who named the subfamily, likened them to smelt.<ref name="AmericanCharacidae2">{{cite book |last1=Eigenmann |first1=Carl H. |url=https://www.biodiversitylibrary.org/page/4372702 |title=The American Characidae |last2=Meyers |first2=George S. |date=1917–1929 |publisher=Cambridge |pages=493–499 |access-date=3 February 2022}}</ref> Their scales are often brightly colored or reflective, and this, combined with their small size, makes them a potential target for the aquarium industry.<ref>{{Cite journal |last1=Lourenço da Silva |first1=E. |last2=Piscor |first2=D. |last3=Ponzeto |first3=J. M. |last4=Centofante |first4=L. |last5=Alves |first5=A. L. |last6=Parise-Maltempi |first6=P. P. |year=2012 |title=Cytogenetic characterisation of the ornamental freshwater fish, Piabucus melanostomus (Iguanodectinae) from Brazilian wetlands and its relation with species of Characidae basal group |url=http://link.springer.com/10.1007/s11160-011-9238-2 |journal=Reviews in Fish Biology and Fisheries |language=en |volume=22 |issue=2 |pages=477–484 |doi=10.1007/s11160-011-9238-2 |issn=0960-3166 |s2cid=17712507|url-access=subscription }}</ref>
The dorsal fin is located behind the middle of the body and usually behind the start of the pelvic fin, though sometimes the dorsal and pelvic fins are on the same line of origin.<ref name=":02">{{Cite journal |last=Vari |first=Richard P. |date=26 January 1977 |title=Notes on the characoid subfamily Iguanodectinae, with a description of a new species. |url=http://hdl.handle.net/2246/2012 |journal=American Museum Novitates |issue=2612 |via=AMNH Digital Repository |hdl=2246/2012}}</ref><ref>{{Cite journal |last=Mirande |first=Juan Marcos |date=2010 |title=Phylogeny of the family Characidae (Teleostei: Characiformes): from characters to taxonomy |journal=Neotropical Ichthyology |language=en |volume=8 |issue=3 |pages=385–568 |doi=10.1590/S1679-62252010000300001 |issn=1679-6225 |doi-access=free |hdl-access=free |hdl=11336/77449}}</ref> All members of the subfamily have a small dorsal adipose fin.<ref name=":12">{{Cite journal |last=Böhlke |first=James E. |date=1954-02-01 |title=XV.—Studies on fishes of the family Characidae.—No. 6. A synopsis of the Iguanodectinae |url=https://doi.org/10.1080/00222935408651699 |journal=Annals and Magazine of Natural History |volume=7 |issue=74 |pages=97–104 |doi=10.1080/00222935408651699 |issn=0374-5481|url-access=subscription }}</ref> ''Piabucus'' typically have longer pectoral fins and a deeper chest than ''Iguanodectes'' (sometimes described as a more pronounced "pectoral keel").<ref name=":2">{{Cite book |title=Check list of the freshwater fishes of South and Central America |date=2003 |publisher=EDIPUCRS |others=Roberto E. Reis, Sven O. Kullander, Carl J. Ferraris, Pontifícia Universidade Católica do Rio Grande do Sul. Museu de Ciências e Tecnologia |isbn=85-7430-361-5 |location=Porto Alegre, Brasil |oclc=54496178}}</ref> The lateral line is complete in all species.<ref name=":12" /> The species ''Iguanodectes geisleri'' has some morphological differences when compared to its congeners; its dorsal fin originates in the middle of the body, as opposed to behind the middle, and its anal fin is shorter in length.<ref name=":2" />
The mouth is small, terminal, and does not extend past or under the eye.<ref name=":12" /> The maxilla is equipped with multicuspid incisor teeth, contracted at the base and flaring outwards.<ref name=":02" /> The premaxilla has one or two teeth on each side in all species, except for ''Piabucus melanostomus'', which lacks this "outer set".<ref name=":12" /> This dentition is primarily used for an herbivorous diet, at least in ''Iguanodectes'', but little is known of the subfamily's ecology outside of this.<ref name=":2" />
== Habitat == Iguanodectids are found in South America, spread all across the northern half of the continent.<ref name="SiBBr">{{cite web|title=Iguanodectidae|url=https://ala-bie.sibbr.gov.br/ala-bie/species/158903|access-date=3 February 2022|website=SiBBr}}</ref><ref name="GBIF">{{Cite web|title=Iguanodectidae|url=https://www.gbif.org/species/7009509|access-date=2022-02-03|website=GBIF|language=en}}</ref> Though they primarily inhabit freshwater, Iguanodectid fishes are known to tolerate brackish water as well.<ref name="FishBase">{{FishBase family|month=February|year=2022|family=Iguanodectidae}}</ref> Habitat destruction, by way of land development and aquaculture, is the biggest threat to members of Iguanodectidae, though evaluated species are mostly considered least concern by the International Union for the Conservation of Nature (IUCN).<ref>{{Cite web|title=Red List Search: Iguanodectidae|url=https://www.iucnredlist.org/search/stats?taxonomies=64687286&searchType=species|access-date=2 February 2022|website=IUCN Red List}}</ref>
They can be found in the Amazon, Orinoco, Tocantins, and Paraguay rivers, as well as all major tributaries of the Amazon.<ref name=":2"/> Of these, the Paraguay is the least-populated; Iguanodectinae is only represented therein by a few species in the genus ''Piabucus''.<ref>{{Cite journal |last1=Borba |first1=Rafael Splendore de |last2=Silva |first2=Edson Lourenço da |last3=Ponzetto |first3=Josi Margarete |last4=Pozzobon |first4=Allan Pierre Bonetti |last5=Centofante |first5=Liano |last6=Alves |first6=Anderson Luis |last7=Parise-Maltempi |first7=Patrícia Pasquali |date=March 2013 |title=Genetic structure of the ornamental tetra fish species Piabucus melanostomus Holmberg, 1891 (CHARACIDAE, IGUANODECTINAE) in the Brazilian Pantanal wetlands inferred by mitochondrial DNA sequences |journal=Biota Neotropica |language=en |volume=13 |pages=42–46 |doi=10.1590/S1676-06032013000100004 |issn=1676-0611 |doi-access=free |hdl-access=free |hdl=11449/19632}}</ref> When in captivity, species from both genera have been observed to be intolerant of poor water conditions, demonstrating a preference for a well-oxygenated environment.<ref name=":3">{{cite web |title=Iguanodectes spilurus (Green Line Lizard Tetra) |url=https://www.seriouslyfish.com/species/iguanodectes-spilurus/ |access-date=3 February 2022 |website=Seriously Fish}}</ref><ref name=":4">{{Cite web |title=Piabucus dentatus (Piabuco Tetra) — Seriously Fish |url=https://www.seriouslyfish.com/species/piabucus-dentatus/ |access-date=2022-02-08 |website=Seriously Fish}}</ref> They seem to prefer swimming near the surface of the water.
== Classification == Iguanodectidae is in the order Characiformes, with three extant genera - ''Bryconops'', ''Iguanodectes'', and ''Piabucus''.<ref name="GBIF" /><ref>{{Cite journal|last1=Melo|first1=Bruno F.|last2=Benine|first2=Ricardo C.|last3=Silva|first3=Gabriel S. C.|last4=Avelino|first4=Gleisy S.|last5=Oliveira|first5=Claudio|date=2016-01-01|title=Molecular phylogeny of the Neotropical fish genus Tetragonopterus (Teleostei: Characiformes: Characidae)|url=https://www.sciencedirect.com/science/article/pii/S1055790315003255|journal=Molecular Phylogenetics and Evolution|language=en|volume=94|issue=Pt B|pages=709–717|doi=10.1016/j.ympev.2015.10.022|pmid=26541240|bibcode=2016MolPE..94..709M |hdl=11449/161044|issn=1055-7903|hdl-access=free}}</ref> Said genera used to be classified in the family Characidae, but have since been reclassified in order to keep Characidae monophyletic.<ref name="Phylogenetics" />
Iguanodectidae contains the following genera:<ref name = "Cof family>{{Cof family|family=Iguanodectidae|access-date=21 August 2025}}</ref> {{Linked genus list | Bryconops | Kner, 1858 | Iguanodectes | Cope, 1872 | Piabucus | Oken, 1917 }}
''Bryconops'' is the most speciose genus, with 21 valid species.<ref name="FishBaseBryconops" /> ''Iguanodectes'' is next-largest with 8, and ''Piabucus'' has the fewest at 3.<ref name="FishBaseIguanodectes" /><ref name="FishBasePiabucus" />
''Iguanodectes'' and ''Piabucus'' are largely considered to make up the subfamily Iguanodectinae, with ''Bryconops'' becoming its own separate clade, but this is a matter of debate. Several sources accept the subfamily Iguanodectinae as its own entity,<ref>{{Cite web|title=Iguanodectidae Eigenmann, 1909 - Ocean Biodiversity Information System|url=https://portal.obis.org/taxon/826575|access-date=2022-02-03|website=portal.obis.org}}</ref><ref>{{Cite web|title=WoRMS - World Register of Marine Species - Iguanodectidae Eigenmann, 1909|url=https://www.marinespecies.org/aphia.php?p=taxdetails&id=826575|access-date=2022-02-03|website=www.marinespecies.org}}</ref> but others consider it synonymous with Iguanodectidae<ref>{{Cite web|title=IRMNG - Iguanodectidae|url=https://www.irmng.org/aphia.php?p=taxdetails&id=120681|access-date=2022-02-03|website=Interim Register of Marine and Nonmarine Genera}}</ref><ref>{{Cite web|last=|title=Taxonomy browser (Iguanodectidae)|url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=1489783|access-date=2022-02-03|website=NCBI}}</ref> or simply do not acknowledge it,<ref name=":0">{{Cite web|last=|first=|title=Eschmeyer's Catalog of Fishes Classification|url=https://www.calacademy.org/eschmeyers-catalog-of-fishes-classification|access-date=2022-02-03|website=California Academy of Sciences|language=en}}</ref> uniting the genera therein. ITIS considers it synonymous with Characidae, which is a reflection of its older classification.<ref>{{Cite web|title=ITIS - Report: Iguanodectinae|url=https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=638840#null|access-date=2022-02-03|website=www.itis.gov}}</ref>
Iguanodectinae, when first officially classified by Carl H. Eigenmann in 1909, was placed in the family Characidae, and only contained the genus ''Iguanodectes'';<ref name=":1">{{Cite book|last=Eigenmann|first=Carl H.|url=https://www.biodiversitylibrary.org/bibliography/11953|title=Catalogue and bibliography of the fresh water fishes of the Americas south of the Tropic of Cancer|date=1910|publisher=Press of the New Era Printing Co.|location=Lancaster, Pa.|doi=10.5962/bhl.title.11953}}</ref> by 1929, it had grown to include the genus Piabucus.<ref name="AmericanCharacidae" /> Through 1977, this remained the case.<ref>{{Cite journal|last=Vari|first=Richard P.|date=26 January 1977|title=Notes on the characoid subfamily Iguanodectinae, with a description of a new species.|url=http://hdl.handle.net/2246/2012|journal=American Museum Novitates|issue=2612|hdl=2246/2012|via=AMNH Digital Repository}}</ref> In 2011, Iguanodectinae was found to be closely related to ''Bryconops'', and the two clades were combined in Iguanodectidae.<ref name="Phylogenetics">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): [http://www.biomedcentral.com/content/pdf/1471-2148-11-275.pdf 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''</ref>
== History == The family Iguanodectidae was resurrected from Eigenmann's work in 2011 by Oliveira et al. to contain Iguanodectinae and ''Bryconops''.<ref name="FishBase" /><ref name="Phylogenetics" /> Iguanodectinae itself was classified in 1909, and therefore Iguanodectidae is often considered to originate in the same year, despite the recent nature of the study.<ref name=":0" />
== In aquaria == left|thumb|An unidentified ''Iguanodectes sp.''
Though data is limited, it is known that ''Bryconops colanegra'',<ref>Echevarría, G. 2019. Bryconops colanegra. The IUCN Red List of Threatened Species 2019: e.T118038855A118038861. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T118038855A118038861.en. Accessed on 03 February 2022.</ref> ''Bryconops colaroja'',<ref>Echevarría, G. 2019. Bryconops colaroja. The IUCN Red List of Threatened Species 2019: e.T118038882A118038887. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T118038882A118038887.en. Accessed on 03 February 2022.</ref> and ''Piabucus dentatus''<ref>Taphorn, D.C., DoNascimiento, C., Herrera-Collazos, E.E., Rodríguez-Olarte, D., Usma, S. & Villa-Navarro, F. 2021. Piabucus dentatus. The IUCN Red List of Threatened Species 2021: e.T49830090A176108340. https://dx.doi.org/10.2305/IUCN.UK.2021-2.RLTS.T49830090A176108340.en. Accessed on 03 February 2022.</ref> are seen in the ornamental fish trade. ''Iguanodectes geisleri'' is rare, but is sold under the name "red line lizard tetra".<ref>{{cite web|title=Red Line Lizard Tetra (Iguanodectes geisleri)|url=https://www.aqua-imports.com/product/red-line-lizard-tetra-iguanodectes-geisleri/|access-date=3 February 2022|website=Aqua-Imports}}</ref> One of its congeners, ''Iguanodectes spilurus'', is called the "green line lizard tetra", and is sensitive to poor water conditions.<ref>{{cite web|title=Iguanodectes spilurus (Green Line Lizard Tetra)|url=https://www.seriouslyfish.com/species/iguanodectes-spilurus/|access-date=3 February 2022|website=Seriously Fish}}</ref>
Though not as popular as many other species of tetra, several members of Iguanodectinae are seen in the aquarium trade. ''Piabucus dentatus'', sometimes called the Piabuco tetra, is taken from the wild for such purposes, but is not at risk of going extinct from it.<ref name=":4"/><ref>Taphorn, D.C., DoNascimiento, C., Herrera-Collazos, E.E., Rodríguez-Olarte, D., Usma, S. & Villa-Navarro, F. 2021. ''Piabucus dentatus''. ''The IUCN Red List of Threatened Species'' 2021: e.T49830090A176108340. https://dx.doi.org/10.2305/IUCN.UK.2021-2.RLTS.T49830090A176108340.en. Accessed on 08 February 2022.</ref> Reports from hobbyists as recently as "the summer of 2018" show that such collection is still ongoing.<ref>{{Cite web |last=Fischer |first=Eckhard |date=3 January 2020 |title=Piabucus dentatus - A Rare, Unusual Tetra |url=https://www.andreae-hi.de/piabucus-dentatus-ein-seltener-ungewoehnlicher-salmler/ |access-date=8 February 2022 |website=Hildesheim Terrarium and Aquarium Club}}</ref> It tends to form groups, so aquarists are recommended to house as many as at least 6 at a time.<ref name=":4" /><ref>{{Cite web |title=Piabuco tetra (Piabucus dentatus) |url=https://en.aqua-fish.net/fish/piabuco-tetra |access-date=2022-02-08 |website=Aqua-Fish Database}}</ref> This goes for the other species of ''Piabucus'' as well; all three are sometimes grouped as ''Piabucus sp.'' and called "chin tetras".<ref>{{Cite web |date=June 2007 |title=Chin tetra, Piabucus sp. - Practical Fishkeeping |url=https://www.practicalfishkeeping.co.uk/features/chin-tetra-piabucus-sp-/ |access-date=2022-02-08 |website=www.practicalfishkeeping.co.uk}}</ref> This is likely due to distinct markings on the lower jaw.<ref name=":4" />
Fish from ''Iguanodectes'' are slightly more common than from ''Piabucus,'' but are still infrequent in the trade. ''I. geisleri'' is sold under the name "red line lizard tetra", and ''I. spilurus'' has the name "green line lizard tetra".<ref name=":3"/><ref>{{cite web |title=Red Line Lizard Tetra (Iguanodectes geisleri) |url=https://www.aqua-imports.com/product/red-line-lizard-tetra-iguanodectes-geisleri/ |access-date=3 February 2022 |website=Aqua-Imports}}</ref> ''I. adujai'' looks quite similar to ''I. geisleri'', so is sometimes part of the same stock.<ref>{{Cite web |title=Iguanodectes adujai — Seriously Fish |url=https://www.seriouslyfish.com/species/iguanodectes-adujai/ |access-date=2022-02-08 |website=Seriously Fish}}</ref>
== References == {{Reflist}}
{{Taxonbar|from=Q18182928}}
Category:Iguanodectidae Category:Freshwater fish of South America Category:Characiformes families Category:Characoidei