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Brief Summary

    Oscar (fish): Brief Summary
    provided by wikipedia

    The oscar (Astronotus ocellatus) is a species of fish from the cichlid family known under a variety of common names, including tiger oscar, velvet cichlid, and marble cichlid. 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. The fish has been introduced to other areas, including China, Australia, and the United States. It is considered a popular aquarium fish in Europe and the U.S.

    Brief Summary
    provided by EOL authors
    Astronotus ocellatus is a species of fish from the cichlid family, originally described by Louis Agassiz in 1831, although he mistakenly classified it in the marine genus Lobotes. The largest of the new world cichlids, they can live 10-20 years and reach up to a maximum length of 45cm (18 inches) long, although they are most commonly found 25-30 cm (10-12 inches) in length and 1.6 kilograms (3.5 lb) in weight. A popular aquarium fish, Astronotus ocellatus has many common names, including oscar, tiger oscar, velvet cichlid, or marble cichlid, which reflect a number of bred ornamental varieties, including long-finned varieties and various color morphs. Oscars are native to the Amazon river basin, especially shallow, quiet floodplains and swamps. Native oscars usually show characteristic orange ringed, bilateral ocelli (eyespots) at the base of their tail which have been shown to dissuade predators and also function in sexual selection, as these fish are very visually oriented. Suction feeders, A. ocellatus are omnivorous, eating invertebrates such as flies, worms, crayfish, some small fish, fruit that falls into water, and large oscars will even eat small vertebrates, such as mice. Oscars are an esteemed food species in South America, although not commonly eaten elsewhere, as they grow too slowly for aquaculture. Escaped ornamentals and individuals purposely introduced into waterways have established wild populations in Asia, China and North America. (Beeching, 1995; Froese 2011; Griffioen 1999; Nico and Fuller 2012; Robbins; Wikipedia 2012; Winemiller 1990)

Comprehensive Description

    Oscar (fish)
    provided by wikipedia

    The oscar (Astronotus ocellatus) is a species of fish from the cichlid family known under a variety of common names, including tiger oscar, velvet cichlid, and marble cichlid.[1] 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.[2][3] The fish has been introduced to other areas, including China, Australia, and the United States. It is considered a popular aquarium fish in Europe and the U.S.[4][5][6]

    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.[7] The species also has a number of junior synonyms: Acara compressus, Acara hyposticta, Astronotus ocellatus zebra, and Astronotus orbiculatus.[8]

    Description

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    Ocelli on dorsal fin and caudal peduncle

    A. ocellatus examples have been reported to grow to about 45 cm (18 in) in length and 1.6 kilograms (3.5 lb) in weight.[1] 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.[5] 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.[7][9] The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics.[10] Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.[7]

    Distribution and habitat

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    Two tiger oscars

    A. ocellatus is native to Peru, Ecuador, Colombia, Brazil, and French Guiana, 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.[1][2] In its natural environment, the species typically occurs in slow-moving white-water habitats, and has been observed sheltering under submerged branches.[5] Feral populations also occur in China,[11] northern Australia,[12] and Florida, USA[13] 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).[14]

    Reproduction

    Although the species is widely regarded as sexually monomorphic,[5] males have been suggested to grow more quickly,[citation needed] and in some naturally occurring strains, males are noted to possess dark blotches on the base of their dorsal fins.[6][7] The species reaches sexual maturity around one year of age,[citation needed] and continues to reproduce for 9–10 years.[citation needed] Frequency and timing of spawning may be related to the occurrence of rain.[15] A. ocellatus fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild is scarce.

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    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 1,000 to 3,000 eggs.[citation needed] Like most cichlids, A. ocellatus practices brood care, although the duration of brood care in the wild remains unknown.[6]

    In the aquarium

    The oscar is one of the most popular cichlids in the aquarium hobby.

    Food

    Most fish eaten by A. ocellatus in the wild are relatively sedentary catfish, including Bunocephalus, Rineloricaria, and Ochmacanthus species.[9] The species uses a suction mechanism to capture prey,[16] and has been reported to exhibit "laying-on-side" death mimicry in a similar fashion to Parachromis friedrichsthalii and Nimbochromis livingstonii.[17][18] The species also has an absolute requirement for vitamin C, and develops health problems in its absence.[19] Captive oscars generally eat fish food designed for large carnivorous fish: crayfish, worms, and insects (such as flies, crickets and grasshoppers).[20]

    Territorial behavior

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    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 inside the aquarium or lake. The size of the territory varies depending on the size and aggressiveness of the fish based on its surroundings. Once the oscar establishes a territory, it will vigorously defend it by chasing away other fish.[21]

    Varieties

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    A 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, leucistic, and xanthistic forms. A. ocellatus with marbled patches of red pigmentation are sold as red tiger oscars, while those strains with mainly red colouration of the flanks are frequently sold under the trade name of red oscars.[22] The patterning of red pigment differs between individuals; in the United Kingdom, one A. ocellatus reportedly had markings that resembled the Arabic word for "Allah".[23] In recent years long-finned varieties have also been developed. The species is also occasionally artificially coloured by a process known as painting.[24]

    References

    1. ^ a b c Froese, R. and D. Pauly. Editors. "Astronotus ocellatus, Oscar". FishBase. Archived from the original on 2007-09-29. Retrieved 2007-03-16.CS1 maint: Extra text: authors list (link) .mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
    2. ^ a b Kullander SO. "Cichlids: Astronotus ocellatus". Swedish Museum of Natural History. Retrieved 2007-03-16.
    3. ^ Kohler, CC; et al. "Aquaculture Crsp 22nd Annual Technical Report" (PDF). Oregon State University, USA. Retrieved 2007-03-16.
    4. ^ 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
    5. ^ a b c d Staeck, Wolfgang; Linke, Horst (1995). American Cichlids II: Large Cichlids: A Handbook for Their Identification, Care, and Breeding. Germany: Tetra Press. ISBN 1-56465-169-X.
    6. ^ a b c Loiselle, Paul V. (1995). The Cichlid Aquarium. Germany: Tetra Press. ISBN 1-56465-146-0.
    7. ^ a b c d Robert H. Robins. "Oscar". Florida Museum of Natural History. Retrieved 2007-03-18.
    8. ^ Froese, R. and D. Pauly. Editors. "Synonyms of Astronotus ocellatus". FishBase. Archived from the original on September 29, 2007. Retrieved 2007-03-21.CS1 maint: Extra text: authors list (link)
    9. ^ a b Winemiller KO (1990). "Caudal eye spots as deterrents against fin predation in the neotropical cichlid Astronotus ocellatus" (PDF). Copeia. 3 (3): 665–673. doi:10.2307/1446432. JSTOR 1446432. Archived from the original (PDF) on 2012-05-04.
    10. ^ Beeching, SC (1995). "Colour pattern and inhibition of aggression in the cichlid fish Astronotus ocellatus". Journal of Fish Biology. 47: 50–58. doi:10.1111/j.1095-8649.1995.tb01872.x.
    11. ^ Ma, X.; Bangxi, X.; Yindong, W. & Mingxue, W. (2003). "Intentionally Introduced and Transferred Fishes in China's Inland Waters". Asian Fisheries Science. 16: 279–290.
    12. ^ Department of primary industry and fisheries. "Noxious fish – species information". Queensland Government, Australia. Archived from the original on 2007-08-29. Retrieved 2007-03-16.
    13. ^ United States Geological Survey. "NAS – Species FactSheet Astronotus ocellatus (Agassiz 1831)". United States Government. Retrieved 2007-03-17.
    14. ^ Shafland, P. L. & J. M. Pestrak (1982). "Lower lethal temperatures for fourteen non-native fishes in Florida". Environmental Biology of Fishes. 7 (2): 139–156. doi:10.1007/BF00001785.
    15. ^ Pinto Paiva, M & Nepomuceno, FH (1989). "On the reproduction in captivity of the oscar, Astronotus ocellatus (Cuvier), according to the mating methods (Pisces – Cichlidae)". Amazoniana. 10: 361–377.
    16. ^ Waltzek,TB and Wainwright, PC (2003). "Functional morphology of extreme jaw protrusion in Neotropical cichlids". Journal of Morphology. 257 (1): 96–106. doi:10.1002/jmor.10111. PMID 12740901.CS1 maint: Multiple names: authors list (link)
    17. ^ Tobler, M. (2005). "Feigning death in the Central American cichlid Parachromis friedrichsthalii". Journal of Fish Biology. 66 (3): 877–881. doi:10.1111/j.0022-1112.2005.00648.x.
    18. ^ Gibran,FZ. (2004). Armbruster, J. W., ed. "Dying or illness feigning: An unreported feeding tactic of the Comb grouper Mycteroperca acutirostris (Serranidae) from the Southwest Atlantic". Copeia. 2004 (2): 403–405. doi:10.1643/CI-03-200R1. JSTOR 1448579.
    19. ^ Fracalossi, DM; Allen, ME; Nicholsdagger, DK & Oftedal, OT (1998). "Oscars, Astronotus ocellatus, Have a Dietary Requirement for Vitamin C". The Journal of Nutrition. 128 (10): 1745–1751. PMID 9772145.
    20. ^ Kmuda. "Oscar Fish Diet". Retrieved 23 May 2012.
    21. ^ "Oscar Fish Lover". OFL. Retrieved 19 May 2013.
    22. ^ Sandford, Gina; Crow, Richard (1991). The Manual of Tank Busters. USA: Tetra Press. ISBN 3-89356-041-6.
    23. ^ BBC News (2006-01-31). "Tropical fish 'has Allah marking'". BBC, UK. Retrieved 2007-03-18.
    24. ^ Mike Giangrasso. "Death by Dyeing – dyed fish list". Death by Dyeing.org. Retrieved 2007-03-18.
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Distribution

    Distribution
    provided by Animal Diversity Web

    These fish are found in the Amazon River basin, from the Orinoco River to the Rio Paraguay, throughout Venezuela, Guyana, and Paraguay. (The Aquarium Encyclopedia, 1983.)

    Biogeographic Regions: neotropical (Native )

Morphology

    Morphology
    provided by Animal Diversity Web

    Compared to other fishes, Astronotus ocellatus has a slender, laterally compressed body, and a blunt head with a large mouth and protruding jaw. Colors vary greatly among geographic regions and individuals, but most are dark green to black, with red stripes along its back and a red circle on the base of the tail fin. The adult fish grows up to 35 cm long. Males and females are visually indistinguishable. (Gracyalny, 1996.)

    Range mass: 2 to 4 kg.

    Other Physical Features: bilateral symmetry

Habitat

    Habitat
    provided by Animal Diversity Web

    Found in the tropical lowlands of South America, A. ocellatus prefers the floodplains and swamps of the Amazon River basin. They are most comfortable in water about 25 degrees Celsius, or slightly higher for breeding. (Kullander, 1996)

    Aquatic Biomes: rivers and streams

Trophic Strategy

    Trophic Strategy
    provided by Animal Diversity Web

    Although these predators are not at all choosy, they feed mostly on insect larvae and smaller fish. Their feeding habits require that Oscars have excellent eyesight. Because of this, they have been the subject of numerous studies concerning eyesight in fish. (The Aquarium Encyclopedia, 1983, Andison and Sivak, 1996)

Behavior

    Behavior
    provided by Animal Diversity Web

    Perception Channels: tactile ; chemical

Reproduction

    Reproduction
    provided by Animal Diversity Web

    Though they can become much larger, A. ocellatus are sexually mature soon in life, usually by the time they are 12 cm long. These fish exhibit a high degree of parental care. After spawning in open water, the eggs are laid on a piece of ground that has been cleared by one of the parents. After three or four days, the eggs hatch. The brood is then transported to a sandy hollow for about one week. Young fish have been observed clinging to their parents with their mouths, even after they are able to swim freely. (The Aquarium Encyclopedia, 1983)

Conservation Status

    Conservation Status
    provided by Animal Diversity Web

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Benefits

    Benefits
    provided by Animal Diversity Web

    As a popular aquarium fish, A ocellatus has some obvious economic importance to humans. Additionally, it has been used by biologists in numerous studies of fish, including studies on behavior, eyesight, auditory systems, and swim bladders.