oscar (fish)

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.{{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}} The species also has a number of junior synonyms: Acara compressus, Acara hyposticta, Astronotus ocellatus zebra, and Astronotus orbiculatus.{{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 }}

File:Astronotus ocellatus (Agassiz 1831) (Rio Negro, Manaos, Brazil).jpg

File:Astronotus ocellatus05.jpg

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. The wild-caught forms of the species are typically darkly coloured with yellow-ringed spots or ocelli on the caudal peduncle and on the dorsal fin. 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.{{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}} The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics.{{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}} Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.

File:Two Tiger Oscar.jpg

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, Içá, Negro, Solimões, and Ucayali River systems, and also in the Approuague and Oyapock River drainages.{{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}} In its natural environment, the species typically occurs in slow-moving white-water habitats, and has been observed sheltering under submerged branches.{{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 }} Feral populations also occur in China,{{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 }} northern Australia,{{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}} and Florida, USA{{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}} 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 °C (55.22 °F).{{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 }}

Although the species is widely regarded as sexually monomorphic, 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. The species reaches sexual maturity around one year of age,{{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}} and continues to reproduce for 9–10 years. Frequency and timing of spawning may be related to the occurrence of rain.{{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}} A. ocellatus fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild is scarce.

File:oscaroscar.JPG

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. Like most cichlids, A. ocellatus practices brood care, although the duration of brood care in the wild remains unknown.

File:Astronotus ocellatus 2.jpg 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}}

Oscar fish are omnivores.

Most fish eaten by A. ocellatus in the wild are relatively sedentary catfish, including Bunocephalus, Rineloricaria, and Ochmacanthus species. The species uses a suction mechanism to capture prey,{{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}} and has been reported to exhibit "lying-on-side" death mimicry in a similar fashion to Parachromis friedrichsthalii and Nimbochromis livingstonii.{{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}}{{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 }} Wild oscars also consume shrimp, snails, insects and insect larvae, as well as fruits and nuts on a seasonal basis.{{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}} The species also has an absolute requirement for vitamin C, and develops health problems in its absence.{{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}} Captive oscars generally eat fish food designed for large carnivorous fish: crayfish, worms, and insects (such as flies, crickets and grasshoppers).{{cite web|title=Oscar Fish Diet|url=https://www.aliveaquarium.com/oscar-fish-food/|access-date=31 Jan 2019}}

File:Felix the partially albino Tiger Oscar.jpg

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 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.{{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}}

File:Long finned oscar.jpg 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, leucistic, and 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.{{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}} 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 painting.{{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}}

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{{Reflist|2}}

{{Wikispecies|Astronotus ocellatus}}

{{Commons category|Astronotus ocellatus}}

{{Taxonbar|from=Q3442}}

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