Editing Oscar (fish)

{{Short description|Species of fish}}
{{Speciesbox
|name = Oscar fish 
|image = Astronotus_ocellatus.jpg
|status = LC
|status_system = IUCN3.1
|status_ref = <ref>{{cite iucn|last=Frederico|first=R. G.|year=2023|title=Astronotus ocellatus|page=e.T49830436A159048790|doi=10.2305/IUCN.UK.2023-1.RLTS.T49830436A159048790.en}}</ref>
|genus = Astronotus
|species = ocellatus
|authority = ([[Louis Agassiz|Agassiz]], 1831)
}}

The '''oscar''' ('''''Astronotus ocellatus''''') is a species of fish from the [[cichlid]] [[family (biology)|family]] known under a variety of common names, including '''tiger oscar''', '''velvet cichlid''', and '''marble cichlid'''.<ref name="fishbase">{{cite web |author=Kullander |first=Sven O. |date=September 29, 2007 |title=Astronotus ocellatus, Oscar |url=http://filaman.uni-kiel.de/summary/SpeciesSummary.php?id=3612 |url-status=dead |archive-url=https://web.archive.org/web/20070929133649/http://filaman.uni-kiel.de/summary/SpeciesSummary.php?id=3612 |archive-date=2007-09-29 |access-date=2007-03-16 |publisher=FishBase}}</ref> In tropical South America, where the species naturally resides, ''A. ocellatus'' specimens are often found for sale as a food fish in the local markets.<ref name="kullander"/><ref>{{cite web|url=http://pdacrsp.oregonstate.edu/pubs/technical/22tch/03-11SDFR1.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://pdacrsp.oregonstate.edu/pubs/technical/22tch/03-11SDFR1.pdf |archive-date=2022-10-09 |url-status=live|title= Aquaculture Crsp 22nd Annual Technical Report|author=Kohler, CC|publisher=Oregon State University, USA|access-date=2007-03-16|display-authors=etal}}</ref> The fish has been introduced to other areas, including India, China, Australia, and the United States. It is considered a popular [[aquarium]] fish in Europe and the U.S.<ref>Keith, P. O-Y. Le Bail & P. Planquette, (2000) Atlas des poissons d'eau douce de Guyane (tome 2, fascicule I). ''Publications scientifiques du Muséum national d'Histoire naturelle'', Paris, France. p. 286</ref><ref name="amcichlidsII"/><ref name="Loiselle">{{cite book |last=Loiselle |first=Paul V. |title=The Cichlid Aquarium |year=1995 |publisher=Tetra Press |location=Germany |isbn=978-1-56465-146-4}}</ref>

==Taxonomy==
The species was originally described by [[Louis Agassiz]] in 1831 as ''[[Lobotes]] ocellatus'', as he mistakenly believed the species was marine; later work assigned the species to the genus ''Astronotus''.<ref name="florida_museum">{{cite web|url=http://www.flmnh.ufl.edu/fish/Gallery/Descript/oscar/oscar.html|title=Oscar|author=Robert H. Robins|publisher=Florida Museum of Natural History|access-date=2007-03-18|archive-date=2007-03-05|archive-url=https://web.archive.org/web/20070305022519/http://www.flmnh.ufl.edu/fish/Gallery/Descript/oscar/oscar.html|url-status=dead}}</ref> The species also has a number of junior synonyms: ''Acara compressus'', ''Acara hyposticta'', ''Astronotus ocellatus zebra'', and ''Astronotus orbiculatus''.<ref>{{cite web|url=http://filaman.uni-kiel.de/Nomenclature/SynonymsList.cfm?ID=3612&GenusName=Astronotus&SpeciesName=ocellatus |title=Synonyms of Astronotus ocellatus |author1=Froese, R. |author2=D. Pauly |publisher=FishBase |access-date=2007-03-21 |url-status=dead |archive-url=https://web.archive.org/web/20070929083732/http://filaman.uni-kiel.de/Nomenclature/SynonymsList.cfm?ID=3612&GenusName=Astronotus&SpeciesName=ocellatus |archive-date=September 29, 2007 }}</ref>
[[File:Astronotus ocellatus (Agassiz 1831) (Rio Negro, Manaos, Brazil).jpg|alt=watercolor of Astronotus ocellatus|thumb|1831 watercolor of Astronotus ocellatus by Jacques Burkhardt. ]]

==Description==
[[File:Astronotus ocellatus05.jpg|thumb|left|Ocelli on dorsal fin and caudal peduncle]]
''A. ocellatus'' examples have been reported to grow to about {{convert|45|cm|in|abbr=on}} in length and {{convert|1.6|kg|lb}} in weight.<ref name="fishbase"/> The wild-caught forms of the species are typically darkly coloured with yellow-ringed spots or [[Eyespot (mimicry)|ocelli]] on the [[caudal peduncle]] and on the [[dorsal fin]].<ref name="amcichlidsII"/> These ocelli have been suggested to function to limit fin-nipping by [[piranha]] (''[[Serrasalmus]]'' spp.), which co-occur with ''A. ocellatus'' in its natural environment.<ref name="florida_museum"/><ref name="winemiller">{{cite journal|url=http://wfsc.tamu.edu/winemiller/lab/W-eyespots-Copeia90.pdf|author=Winemiller KO|year=1990|title=Caudal eye spots as deterrents against fin predation in the neotropical cichlid ''Astronotus ocellatus''|journal=Copeia|volume=3|issue=3|pages=665–673|doi=10.2307/1446432|jstor=1446432|url-status=dead|archive-url=https://web.archive.org/web/20120504031323/http://wfsc.tamu.edu/winemiller/lab/W-eyespots-Copeia90.pdf|archive-date=2012-05-04}}</ref> The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics.<ref>{{cite journal|author=Beeching, SC|year=1995|title= Colour pattern and inhibition of aggression in the cichlid fish Astronotus ocellatus|journal=Journal of Fish Biology|volume=47|pages= 50–58|doi=10.1111/j.1095-8649.1995.tb01872.x}}</ref> Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.<ref name="florida_museum"/>

==Distribution and habitat==
[[File:Two Tiger Oscar.jpg|right|thumb|Two tiger oscars]]
''A. ocellatus'' is native to Brazil, Colombia, Ecuador, Guyana, French Guiana, Suriname, Peru, and Venezuela, and occurs in the [[Amazon River basin]], along the [[Amazon River|Amazon]], [[Içá]], [[Rio Negro (Amazon)|Negro]], [[Solimões]], and [[Ucayali]] River systems, and also in the [[Approuague river|Approuague]] and [[Oyapock River]] drainages.<ref name="fishbase"/><ref name="kullander">{{cite web|url=http://www2.nrm.se/ve/pisces/acara/as_ocell.shtml|title= Cichlids: Astronotus ocellatus|author=Kullander SO.|publisher=Swedish Museum of Natural History|access-date=2007-03-16|archive-date=July 27, 2020|archive-url=https://web.archive.org/web/20200727184834/http://www2.nrm.se/ve/pisces/acara/as_ocell.shtml}}</ref> In its natural environment, the species typically occurs in slow-moving [[Whitewater river (river type)|white-water]] habitats, and has been observed sheltering under submerged branches.<ref name="amcichlidsII">{{cite book |last=Staeck |first=Wolfgang |author2=Linke, Horst |title=American Cichlids II: Large Cichlids: A Handbook for Their Identification, Care, and Breeding |year=1995 |publisher=Tetra Press |location=Germany |isbn=978-1-56465-169-3 }}</ref> Feral populations also occur in China,<ref>{{cite journal|author1=Ma, X. |author2=Bangxi, X. |author3=Yindong, W. |author4=Mingxue, W.  |name-list-style=amp |year=2003|title= Intentionally Introduced and Transferred Fishes in China's Inland Waters|journal=Asian Fisheries Science|volume=16|issue=4 |pages=279–290|doi=10.33997/j.afs.2003.16.4.001 |s2cid=133672039 |doi-access=free }}</ref> northern Australia,<ref>{{cite web|url=http://www2.dpi.qld.gov.au/fishweb/14477.html|title= Noxious fish – species information|author=Department of primary industry and fisheries.|publisher=Queensland Government, Australia|access-date=2007-03-16 |archive-url = https://web.archive.org/web/20070829180030/http://www2.dpi.qld.gov.au/fishweb/14477.html|archive-date = 2007-08-29}}</ref> and [[Florida]], USA<ref>{{cite web|url=https://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=436|title=NAS – Species FactSheet Astronotus ocellatus (Agassiz 1831)|author=United States Geological Survey.|publisher=United States Government|access-date=2007-03-17|archive-url=https://web.archive.org/web/20070502070704/http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=436|archive-date=2007-05-02|url-status=dead}}</ref> as a byproduct of the ornamental fish trade. The species is limited in its distribution by its intolerance of cooler water temperatures, the lower lethal limit for the species is 12.9&nbsp;°C (55.22&nbsp;°F).<ref>{{cite journal|author1=Shafland, P. L.  |author2=J. M. Pestrak |name-list-style=amp |year= 1982|title= Lower lethal temperatures for fourteen non-native fishes in Florida|journal=Environmental Biology of Fishes|volume=7|pages=139–156|doi=10.1007/BF00001785|issue=2|s2cid=22487662 }}</ref>

==Reproduction==
Although the species is widely regarded as [[Sex#Sexual monomorphism|sexually monomorphic]],<ref name="amcichlidsII"/> males have been suggested to grow more quickly,{{citation needed|date=September 2014}} and in some naturally occurring strains, males are noted to possess dark blotches on the base of their dorsal fins.<ref name="Loiselle"/><ref name="florida_museum"/> The species reaches sexual maturity around one year of age,<ref name="animaldiversity.org">{{cite web |last1=Dowdy |first1=Meredith |title=Astronotus ocellatus Marble cichlid (Also: Red oscar; Velvet cichlid) |url=https://animaldiversity.org/accounts/Astronotus_ocellatus/ |website=animaldiversity.org |publisher=University of Michigan Museum of Zoology |access-date=11 September 2020}}</ref> and continues to reproduce for 9–10 years.<ref name="animaldiversity.org"/> Frequency and timing of spawning may be related to the occurrence of rain.<ref>{{cite journal|author1=Pinto Paiva, M  |author2=Nepomuceno, FH  |name-list-style=amp |year=1989|title=On the reproduction in captivity of the oscar, Astronotus ocellatus (Cuvier), according to the mating methods (Pisces – Cichlidae)|journal=Amazoniana|volume=10|pages=361–377}}</ref> ''A. ocellatus'' fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild is scarce.
[[File:oscaroscar.JPG|thumb|200px|right|Young Oscar, about 2 in]]
In captivity, pairs are known to select and clean generally flattened horizontal or vertical surfaces on which to lay their eggs.{{citation needed|date=September 2014}}. Smaller females lay around 300–500 eggs, while larger female oscars can lay about 2,500-3,000 eggs.<ref name="animaldiversity.org"/> Like most cichlids, ''A. ocellatus'' practices brood care, although the duration of brood care in the wild remains unknown.<ref name="Loiselle"/>

==In the aquarium==
[[File:Astronotus ocellatus 2.jpg|thumb|The oscar at the [[Särkänniemi|Särkänniemi Aquarium]] in [[Tampere]], Finland]]
Oscar fish can live in the aquarium with almost any type of fish around the same size as it gets, for example any type of cichlids and predatory fish. {{Citation needed|date=December 2024}}

===Food===
Oscar fish are omnivores.
Most fish eaten by ''A. ocellatus'' in the wild are relatively sedentary [[catfish]], including ''[[Bunocephalus]]'', ''[[Rineloricaria]]'', and ''[[Ochmacanthus]]'' species.<ref name="winemiller" /> The species uses a suction mechanism to capture prey,<ref>{{cite journal|author=Waltzek,TB and Wainwright, PC|year=2003|title=Functional morphology of extreme jaw protrusion in Neotropical cichlids|journal=Journal of Morphology|volume=257|issue=1|pages=96–106|doi=10.1002/jmor.10111|pmid=12740901|s2cid=15051491 |doi-access=free}}</ref> and has been reported to exhibit "lying-on-side" death mimicry in a similar fashion to ''Parachromis friedrichsthalii'' and ''[[Nimbochromis livingstonii]]''.<ref>{{cite journal|author=Tobler, M.|year=2005|title=Feigning death in the Central American cichlid ''Parachromis friedrichsthalii''|journal=Journal of Fish Biology|volume=66|issue=3|pages=877–881|doi=10.1111/j.0022-1112.2005.00648.x}}</ref><ref>{{cite journal|author=Gibran,FZ.|year=2004|editor1-last=Armbruster|editor1-first=J. W.|title=Dying or illness feigning: An unreported feeding tactic of the Comb grouper ''Mycteroperca acutirostris'' (Serranidae) from the Southwest Atlantic|journal=Copeia|volume=2004|issue=2|pages=403–405|doi=10.1643/CI-03-200R1|jstor=1448579|s2cid=85758542 }}</ref> Wild oscars also consume shrimp, snails, insects and insect larvae, as well as fruits and nuts on a seasonal basis.<ref>{{cite web|work=[[Tropical Fish Hobbyist]]|date=June 2007|url=http://www.tfhmagazine.com/details/articles/feeding-oscars-in-the-home-aquarium.htm|title=Feeding Oscars in the Home Aquarium}}</ref> The species also has an absolute requirement for [[vitamin C]], and develops health problems in its absence.<ref>{{cite journal|author1=Fracalossi, DM|author2=Allen, ME|author3=Nicholsdagger, DK|author4=Oftedal, OT|name-list-style=amp|year=1998|title=Oscars, ''Astronotus ocellatus'', Have a Dietary Requirement for Vitamin C|journal=The Journal of Nutrition|volume=128|issue=10|pages=1745–1751|pmid=9772145|doi=10.1093/jn/128.10.1745|doi-access=free}}</ref> Captive oscars generally eat fish food designed for large carnivorous fish: [[crayfish]], worms, and insects (such as flies, crickets and grasshoppers).<ref>{{cite web|title=Oscar Fish Diet|url=https://www.aliveaquarium.com/oscar-fish-food/|access-date=31 Jan 2019}}</ref>

===Territorial behavior===
[[File:Felix the partially albino Tiger Oscar.jpg|175px|left|thumb|An albino oscar]]
Oscars will often lay claim to an area of the aquarium and will be very aggressive towards other fish encroaching on their newly established [[territory (animal)|territory]] inside the aquarium or lake. The size of the territory varies depending on the size and aggressiveness of the fish, and its surroundings. Once the oscar establishes a territory, it will vigorously defend it by chasing away other fish.<ref>{{cite journal|title=Life History and Growth Relationships of Cichla ocellaris, a Predatory South American Cichlid|journal = Biotropica|volume = 12|issue = 2|pages = 144–157|last=Zaret|first=Thomas|date=June 1980|publisher=Association for Tropical Biology and Conservation|jstor = 2387730|doi = 10.2307/2387730}}</ref>

===Varieties===
[[File:Long finned oscar.jpg|right|thumb|A [[Leucism|leucistic]] long-finned oscar]]
A number of ornamental varieties of ''A. ocellatus'' have been developed for the [[aquarium]] industry. These include forms with greater intensity and quantities of red marbling across the body, [[albino]], [[Leucism|leucistic]], and [[Xanthochromism|xanthistic]] forms. ''A. ocellatus'' with marbled patches of red pigmentation are sold as red tiger oscars, while those strains with the mainly red colouration of the flanks are frequently sold under the trade name of red oscars.<ref name="tankbusters">{{cite book |last=Sandford |first=Gina |author2=Crow, Richard |title=The Manual of Tank Busters|year=1991 |publisher=Tetra Press |location=USA|isbn=978-3-89356-041-7}}</ref> The patterning of red pigment differs between individuals. In recent years long-finned varieties have also been developed. The species is also occasionally artificially coloured by a process known as [[painted fish|painting]].<ref>{{cite web|url=http://www.deathbydyeing.org/colormedead.htm|title= Death by Dyeing – dyed fish list|author=Mike Giangrasso|publisher=Death by Dyeing.org|access-date=2007-03-18}}</ref>
{{Clear}}

==References==
{{Reflist|2}}

{{Wikispecies|Astronotus ocellatus}}
{{Commons category|Astronotus ocellatus}}

{{Taxonbar|from=Q3442}}

[[Category:Astronotus|Oscar (fish)]]
[[Category:Cichlid fish of Brazil]]
[[Category:Freshwater fish of Colombia]]
[[Category:Fish of the Amazon basin]]
[[Category:Taxa named by Louis Agassiz]]
[[Category:Fish described in 1831]]