Oscar (fish)

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Oscar fish
Astronotus ocellatus.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cichliformes
Family: Cichlidae
Genus: Astronotus
Species:
A. ocellatus
Binomial name
Astronotus ocellatus
(Agassiz, 1831)

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. [2] 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. [3] [4] 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. [5] [6] [7]

Contents

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. [8] The species also has a number of junior synonyms: Acara compressus, Acara hyposticta, Astronotus ocellatus zebra, and Astronotus orbiculatus. [9]

1831 watercolor of Astronotus ocellatus by Jacques Burkhardt. Astronotus ocellatus (Agassiz 1831) (Rio Negro, Manaos, Brazil).jpg
1831 watercolor of Astronotus ocellatus by Jacques Burkhardt.

Description

Ocelli on dorsal fin and caudal peduncle Astronotus ocellatus05.jpg
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. [2] 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. [6] 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. [8] [10] The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics. [11] Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads. [8]

Distribution and habitat

Two tiger oscars Two Tiger Oscar.jpg
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, Içá, Negro, Solimões, and Ucayali River systems, and also in the Approuague and Oyapock River drainages. [2] [3] In its natural environment, the species typically occurs in slow-moving white-water habitats, and has been observed sheltering under submerged branches. [6] Feral populations also occur in China, [12] northern Australia, [13] and Florida, USA [14] 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). [15]

Reproduction

Although the species is widely regarded as sexually monomorphic, [6] 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. [7] [8] The species reaches sexual maturity around one year of age, [16] and continues to reproduce for 9–10 years. [16] Frequency and timing of spawning may be related to the occurrence of rain. [17] A. ocellatus fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild is scarce.

Young Oscar, about 2 in Oscaroscar.JPG
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 ]. Smaller females lay around 300–500 eggs, while larger female oscars can lay about 2,500-3,000 eggs. [16] Like most cichlids, A. ocellatus practices brood care, although the duration of brood care in the wild remains unknown. [7]

In the aquarium

The oscar at the Sarkanniemi Aquarium in Tampere, Finland Astronotus ocellatus 2.jpg
The oscar at the 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

Food

Oscar fish are omnivores. Most fish eaten by A. ocellatus in the wild are relatively sedentary catfish, including Bunocephalus , Rineloricaria , and Ochmacanthus species. [10] The species uses a suction mechanism to capture prey, [18] and has been reported to exhibit "lying-on-side" death mimicry in a similar fashion to Parachromis friedrichsthalii and Nimbochromis livingstonii . [19] [20] Wild oscars also consume shrimp, snails, insects and insect larvae, as well as fruits and nuts on a seasonal basis. [21] The species also has an absolute requirement for vitamin C, and develops health problems in its absence. [22] Captive oscars generally eat fish food designed for large carnivorous fish: crayfish, worms, and insects (such as flies, crickets and grasshoppers). [23]

Territorial behavior

An albino oscar Felix the partially albino Tiger Oscar.jpg
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, and its surroundings. Once the oscar establishes a territory, it will vigorously defend it by chasing away other fish. [24]

Varieties

A leucistic long-finned oscar Long finned oscar.jpg
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 the mainly red colouration of the flanks are frequently sold under the trade name of red oscars. [25] 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. [26]

Related Research Articles

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Cichlids are fish from the family Cichlidae in the order Cichliformes. Traditionally Cichlids were classed in a suborder, the Labroidei, along with the wrasses (Labridae), in the order Perciformes, but molecular studies have contradicted this grouping. On the basis of fossil evidence, it first appeared in Argentina during the Early Eocene epoch, about 48.6 million years ago; however, molecular clock estimates have placed the family's origin as far back as 67 million years ago, during the late Cretaceous period. The closest living relative of cichlids is probably the convict blenny, and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is large, diverse, and widely dispersed. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.

<span class="mw-page-title-main">Discus (fish)</span> Genus of fishes

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<span class="mw-page-title-main">Painted fish</span> Artificially coloured aquarium fish

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<span class="mw-page-title-main">Firemouth cichlid</span> Species of fish

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<i>Parachromis managuensis</i> Species of cichlid fish

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<span class="mw-page-title-main">Convict cichlid</span> Species of fish

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<span class="mw-page-title-main">Ram cichlid</span> Species of fish

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<span class="mw-page-title-main">Keyhole cichlid</span> Species of fish

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<i>Pelvicachromis pulcher</i> Species of fish

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<i>Mikrogeophagus altispinosus</i> Species of fish

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<i>Laetacara</i> Genus of fishes

Laetacara is a small genus of cichlids native to freshwater habitats in tropical and subtropical South America, ranging from the upper Orinoco River basin in Venezuela to the Paraná River basin Argentina. The genus is also collectively known as the smiling acaras. Like all cichlids, Laetacara species have well-developed brood care.

<i>Mesonauta</i> Genus of fishes

Mesonauta, the flag cichlids, is a small genus of cichlids native to the Amazon, Orinoco, Essequibo, Paraná and Paraguay basins in South America. Mesonauta is included in the subfamily Cichlasomatinae. They occur in various freshwater habitats such as streams and lakes, especially in areas with little water movement and aquatic vegetation. They are generally found in small groups that stay near the water surface. To avoid predators, adults may jump out of the water and juveniles mimic leaves.

<i>Copadichromis borleyi</i> Species of fish

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<span class="mw-page-title-main">Blue acara</span> Species of fish

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<i>Astronotus crassipinnis</i> Species of fish

Astronotus crassipinnis is a South American fish in the cichlid family from the southern Amazon basin and the Paraná–Paraguay basins. It is not as well-known or common in the aquarium trade as its relative, the more northernly distributed oscar. A. crassipinnis reaches up to 25 cm (10 in) in length.

<i>Mesonauta acora</i> Species of fish

Mesonauta acora is a species of cichlid fish endemic to the Amazon Basin of Brazil; specifically, to blackwater in the Xingu and Tocantins River basins in South America. The species was named by François Louis de la Porte, comte de Castelnau in 1855.

References

  1. ↑ Frederico, R. G. (2023). "Astronotus ocellatus". IUCN Red List of Threatened Species . 2023: e.T49830436A159048790. doi: 10.2305/IUCN.UK.2023-1.RLTS.T49830436A159048790.en .
  2. 1 2 3 Kullander, Sven O. (September 29, 2007). "Astronotus ocellatus, Oscar". FishBase. Archived from the original on 2007-09-29. Retrieved 2007-03-16.
  3. 1 2 Kullander SO. "Cichlids: Astronotus ocellatus". Swedish Museum of Natural History. Archived from the original on July 27, 2020. Retrieved 2007-03-16.
  4. ↑ Kohler, CC; et al. "Aquaculture Crsp 22nd Annual Technical Report" (PDF). Oregon State University, USA. Archived (PDF) from the original on 2022-10-09. Retrieved 2007-03-16.
  5. ↑ 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
  6. 1 2 3 4 Staeck, Wolfgang; Linke, Horst (1995). American Cichlids II: Large Cichlids: A Handbook for Their Identification, Care, and Breeding. Germany: Tetra Press. ISBN   978-1-56465-169-3.
  7. 1 2 3 Loiselle, Paul V. (1995). The Cichlid Aquarium. Germany: Tetra Press. ISBN   978-1-56465-146-4.
  8. 1 2 3 4 Robert H. Robins. "Oscar". Florida Museum of Natural History. Archived from the original on 2007-03-05. Retrieved 2007-03-18.
  9. ↑ Froese, R.; D. Pauly. "Synonyms of Astronotus ocellatus". FishBase. Archived from the original on September 29, 2007. Retrieved 2007-03-21.
  10. 1 2 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.
  11. ↑ 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.
  12. ↑ Ma, X.; Bangxi, X.; Yindong, W. & Mingxue, W. (2003). "Intentionally Introduced and Transferred Fishes in China's Inland Waters". Asian Fisheries Science. 16 (4): 279–290. doi: 10.33997/j.afs.2003.16.4.001 . S2CID   133672039.
  13. ↑ 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.
  14. ↑ United States Geological Survey. "NAS – Species FactSheet Astronotus ocellatus (Agassiz 1831)". United States Government. Archived from the original on 2007-05-02. Retrieved 2007-03-17.
  15. ↑ 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. S2CID   22487662.
  16. 1 2 3 Dowdy, Meredith. "Astronotus ocellatus Marble cichlid (Also: Red oscar; Velvet cichlid)". animaldiversity.org. University of Michigan Museum of Zoology. Retrieved 11 September 2020.
  17. ↑ 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.
  18. ↑ 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. S2CID   15051491.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  19. ↑ 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.
  20. ↑ 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. S2CID   85758542.
  21. ↑ "Feeding Oscars in the Home Aquarium". Tropical Fish Hobbyist . June 2007.
  22. ↑ 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. doi: 10.1093/jn/128.10.1745 . PMID   9772145.
  23. ↑ "Oscar Fish Diet" . Retrieved 31 Jan 2019.
  24. ↑ Zaret, Thomas (June 1980). "Life History and Growth Relationships of Cichla ocellaris, a Predatory South American Cichlid". Biotropica. 12 (2). Association for Tropical Biology and Conservation: 144–157. doi:10.2307/2387730. JSTOR   2387730.
  25. ↑ Sandford, Gina; Crow, Richard (1991). The Manual of Tank Busters. USA: Tetra Press. ISBN   978-3-89356-041-7.
  26. ↑ Mike Giangrasso. "Death by Dyeing – dyed fish list". Death by Dyeing.org. Retrieved 2007-03-18.
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