Astronotus ocellatus
Astronotus ocellatus
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Astronotus ocellatus (Agassiz in Spix and Agassiz, 1831)

Common name: Oscar

Synonyms and Other Names: velvet cichlid, red oscar, marble cichlid

Taxonomy: available through www.itis.govITIS logo

Identification: In general, cichlids (Cichlidae) are superficially similar to North American native sunfishes and black basses (Lepomis and Micropterus; family Centrarchidae). Cichlids can be distinguished from centrarchids by a single nostril opening on each side of the head (vs. two openings in centrarchids) and the presence of a discontinuous or two-part lateral line (continuous in centrarchids). For distinguishing characteristics see Kullander (1986) and Page and Burr (1991). The genus is in need of systematic review and future study may reveal that the species in the aquarium trade and in U.S. open waters is another species of Astronotus, not A. ocellatus. Photographs were provided by Kullander (1986) and Axelrod (1993).

Size: 40 cm.

Native Range: Astronotus is native to South America including Orinoco and Amazon basins; also to French Guiana, and to northern part of Paraguay drainage, Parana basin (Kullander 1986).

US auto-generated map Legend USGS Logo
Alaska auto-generated map
Hawaii auto-generated map
Caribbean auto-generated map
Puerto Rico &
Virgin Islands
Guam auto-generated map
Guam Saipan
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences: Oscars have been found dead prior to ice formation on the shoreline at Jewel Lake near Anchorage, Alaska (Alaska Dept of Fish and Game 2002). A single specimen was collected in the Arizona Canal near Peoria, Arizona, between October 1992 and July 1994 (Wright and Sorensen 1995). One specimen was captured by an angler near Hot Springs, Arkansas (Loe 2005). A single specimen was caught in the Kaweah River in Tulare County, California, in 2002 (museum specimen, LACM 56048.001). This species is established in ponds, rock pits, and canals in southern Florida in Broward, Collier, Glades, Hendry (possibly), Miami-Dade, Monroe, and Palm Beach counties, including portions of Everglades National Park and Big Cypress National Preserve (Rivas 1965; Courtenay et al. 1974, 1984; Hogg 1976a, b; Courtenay and Hensley 1979a, b; Loftus and Kushlan 1987; Courtenay and Stauffer 1990; Fury and Morello 1994; Loftus et al. 2004). The species has been taken in other Florida counties but is not known to be established. A single fish was observed in a canal in the Indian River drainage, Brevard County, on 3 July 1990 (J. Snodgrass, personal communication). Thirty-four specimens, 18.5-28 cm TL, were collected by hook and line from canals surrounding water conservation area 3A near Holiday Park, Pasco County, in or before January 1989 (USGS file record). A large specimen was taken by an angler from a river at Hontoon Island in the St. Johns River drainage, west of Orange City, Volusia County, in August 1991 (USGS file record). Records from Alachua County include a single fish taken from a pond near the town of Newberry on 27 October 1983, one fish taken from a stream on the University of Florida campus, no date given (museum specimen), and a fish taken from Green Pond on the University of Florida campus in 2001 (Hill and Cichra 2005). A large specimen, 33.7 cm TL, was taken by an angler from Boy's Club Pond in Panama City, Bay County, on 11 August 1991 (Anonymous 1993). Another fish was collected in Lake Osborne, SE coast near Lantana, Palm Beach County in 2003 (Cocking 2003). In Georgia, a single fish was taken by an angler from Gum Creek in the Flint drainage, Crisp County, on 5 June 1991; a single fish was taken by an angler from the Chattahoochee River, Fulton County, on 27 August 1989 (Gennings, personal communication). It was introduced into Hawaii in the in the 1950s on the islands of Kauai and Oahu (Brock 1960; Shima 1972; Morita 1981; Maciolek 1984; Devick 1991a, b; Sakamoto 2002), water bodies stocked included Nuuanu Reservoir 2 and Wailua Reservoir on Kauai and Wahiawa Reservoir on Oahu (Brock 1960). A single fish was caught in the Kankakee River, Indiana, in 2008 (D. Keller, pers. comm.). A fish identified as Astronotus sp. reportedly was collected from an unspecified public water body in Louisiana; no date was given (Tilyou, personal communication). One specimen was reported from a pond near Fort Meade Army Base in Anne Arundel County, Maryland, in 2003 (B. Lunsford, Maryland Department of Natural Resources, pers. comm.). A single fish was taken by an angler from Congamond Lake in Southwick, Hampden County, Massachusetts, in August 1978; a sight record exists from Amherst, Hampshire County, in 1992; other unconfirmed reports from the state are known (Hartel 1992; Cardoza et al. 1993). A specimen was collected from Simley Pond, Dakota County, Minnesota (Schmidt, unpublished data). A fish was taken by hook and line in a local river in Mississippi, in 1978 (North American Native Fish Association 1978); it also has been referenced for this same state, but with no additional data, by others (e.g., Courtenay et al. 1984; Courtenay and Stauffer 1990). A single fish was collected from a pond along the North Platte River near Cozad, Nebraska, in 1998 (S. Schainost, personal communication). A single fish was caught in the Millstone River near its confluence with the Raritan River in Somerset County, New Jersey, in August 1994 (W. Wakefield, personal communication; photo). A single fish was collected in a lake near Perrysville, Ohio, in July 2000 (Kent 2000), as well as in the Ohio River at Newburg Landing near Toronto, Ohio, in 2009. Specimens occasionally have been collected from unspecified localities in Pennsylvania (Courtenay and Hensley 1979a; Courtenay et al. 1984, 1991; Courtenay and Stauffer 1990). Numerous specimens have been documented in areas of Puerto Rico including establishments in Tortuguero Lagoon, Loiza Reservoir, Las Curias Reservoir, Guajataca Reservoir, La Plata Reservoir, Comerio Reservoir, Cidra Reservoir, Bayamon Reservoir and Aibonito farm pond (Erdsman 1984; Lee et al 1983).  It has been reported from Rhode Island (Courtenay and Hensley 1979a; Courtenay et al. 1984; Courtenay and Stauffer 1990) (the inclusion of Rhode Island is apparently based on a report, poorly documented in our files, of two specimens taken by an angler from a pond in northern part of state in the early 1970s). Single fish were taken both in the Edisto River and in Lake Wylie, South Carolina, in 2004 (Guerin 2004) and 2010 (R. Stroud, SC Department of Natural Resources, pers. comm.) , respectively.  Several Texas records are based on specimens taken by anglers, but no spawning or established populations are known (Howells 1992). Specific Texas sites mentioned in correspondence include Victor Braunig Reservoir near San Antonio, Bexar County (Howells, personal communication), Greenbelt Reservoir, Donley County (Texas Parks and Wildlife Department 2001), and the San Antonio River near San Antonio, Bexar County (Howells, referenced in USGS file records).  They were stocked in Tradinghouse Creek Reservoir [Hallsburg, TX], Matagorda Bay, Sabine Lake (estuary), San Antonio Bay (estuary), Aransas Bay, Lower and Upper Laguna Madre, Galveston Bay, Fairfield Reservoir, Braunig Reservoir, Corpus Christi Bay in 1992 (Waldrip 1993).  Specimens were collected from the following counties in Texas: Bexar, Tom Green, McLennan, Freestone, and Mitchell (Anonymous 1992; Texas Parks and Wildlife Department 1993).  A single specimen was taken from a Virginia Beach, Virginia, area pond during 1987 (Jenkins and Burkhead 1994, based on Southwick, personal communication).  A single fish was caught by an angler in Lake Hortonia, Rutland County, Vermont in 2005 (unknown 2005).  Specimens were collected from a hydro facility trash rack at the Danbury facility on the Yellow River, Burnett County, Wisconsin (Wisconsin DNR).

Ecology: Lower lethal limit is 12°C (Shafland and Pestrak 1982). Extremely tolerant to low oxygen conditions (Muusze et al. 1998), and known to perform aquatic surface respiration to help mitigate hypoxia (Kramer and McClure 1982).

Means of Introduction: The first Florida records were the result of deliberate stockings from an aquarium fish farm in southeastern Dade County in the late 1950s (Courtenay et al. 1974; Courtenay and Hensley 1979a; Courtenay and Stauffer 1990; Jackson 1999). During the same period, attempts were made to popularize the species as a sport fish under the name "velvet cichlid." Anglers have aided dispersal in Florida by transporting fish to new locations (Courtenay et al. 1974). It was sighted at the Anhinga Trail in Everglades National Park in the late 1980s (Loftus and Kushlan 1987). It apparently gained access to the park by way of the South Florida Water Management District's Canal L31W, and it is now considered established (Courtenay 1989). The first introduction of this species into Hawaii was in 1952, for purposes of recreational fishing (Devick 1991a, b); Hawaii's Division of Fish and Game made additional reservoir stockings in 1958; the original source of the Hawaii plants was a small stock obtained from Steinhart Aquarium in San Francisco (Brock 1960). Introductions into all other states and in more northern portions of Florida are apparently the result of aquarium releases (Courtenay and Stauffer 1990; Nico, personal communication).

Status: Established in south Florida, Hawaii, and Puerto Rico. Failed in Alaska, Arizona, California, Georgia, Indiana, Louisiana, Maryland, Massachusetts, Minnesota, Mississippi, Ohio, Nebraska, New Jersey, North Carolina, Pennsylvania, Rhode Island, South Carolina, Texas, Vermont, Virginia, and Wisconsin.

Impact of Introduction: Largely unknown. In 1993, the state of Florida issued a health advisory warning people about eating freshwater fish contaminated with mercury. For portions of south Florida, the oscar was included in the list of fish for which limited consumption was recommended. Oscars are considered potential competitors with native centrarchids (sunfishes) for food and possibly for spawning areas (Courtenay and Hensley 1979a), and as predators on native fishes and invertebrates.

Remarks: Oscars are very common in the aquarium trade. Because they grow large in aquaria and are piscivorous, individuals are likely to be released into natural waters by aquarists loathe to kill their pets. This likely accounts for the numerous instances of single specimen records from both temperate and subtropical states. Unfortunately, the taxonomy of this group is problematic and future research may determine that some oscars in the aquarium trade, as well as those taken in U.S. waters, are not A. ocellatus but another member of the genus (S. O. Kullander, personal communication). To confound the issue, artificial breeding has produced several color variants (Axelrod 1993), and genetic analyses have suggested the presence of mophologically cryptic species within Astronotus (Colatreli et al. 2012). Based on recent reports of the Florida Game and Freshwater Fish Commission, oscars now compose a substantial proportion of the recreational fishery catch in some areas of the Everglades (Fury and Morello 1994), especially when cold temperatures have been absent for several years (Shafland et al. 2008). The distribution and abundance of this species in south Florida fluctuate widely based on the prevalence of cold temperatures (Shafland et al. 2008). The Florida size record was a 1.1 kg, 32 cm TL fish taken from Lake Okeechobee, Palm Beach County, on 16 March 1994 (Ray 1994). Oscars have been established in Miami-Dade County, southeastern Florida, since late 1950s, but began to expand range greatly in late 1970s and early 1980s (Hogg 1976a, b; Courtenay and Stauffer 1990; Fury and Morello 1994).

Voucher specimens: Florida (NCSM 29693; UF 30869, 41396, 44882, 91613, 91898, 91934, 163968, and others); Massachusetts (MCZ 57046).

References: (click for full references)

Alaska Department of Fish and Game. 2002. Alaska aquatic nuisance species management plan. Alaska Department of Fish and Game, Juneau, AK.

Anonymous. 1993. A new exotic state record. Florida Game and Fish, June 1993:12.

Axelrod, H.R. 1993. The most complete colored lexicon of cichlids. Tropical Fish Hobbyist Publications, Inc., Neptune City, NJ.

Cardoza, J.E., G.S. Jones, T.W. French, and D.B. Halliwell. 1993. Exotic and translocated vertebrates of Massachusetts, 2nd edition. Fauna of Massachusetts Series 6. Massachusetts Division of Fisheries and Wildlife, Publication 17223-110-200-11/93-C.R, Westborough, MA.

Cocking, S. 2003. Rush to heavy-traffic area. Miami Herald. June 12, 2003.

Colatreli, O.P., N.V. Meliciano, D. Toffoli, I.P. Farias, and T. Hrbek. 2012. Deep phylogenetic divergence and lack of taxonomic concordance in species of Astronotus (Cichlidae). International Journal of Evolutionary Biology 2012:article ID 915265. doi:10.1155/2012/915265

Courtenay, W.R., Jr. 1989. Exotic fishes in the National Park System. 237-252 in L.K. Thomas, ed. Proceedings of the 1986 conference on science in the national parks, volume 5. Management of exotic species in natural communities. U.S. National Park Service and George Wright Society, Washington, DC.

Courtenay, W.R., Jr., and D.A. Hensley. 1979a. Survey of introduced non-native fishes. Phase I Report. Introduced exotic fishes in North America: status 1979. Report Submitted to National Fishery Research Laboratory, U.S. Fish and Wildlife Service, Gainesville, FL.

Courtenay, W.R., Jr., and D.A. Hensley. 1979b. Range expansion in southern Florida of the introduced spotted tilapia, with comments on environmental impress. Environmental Conservation 6(2):149-151.

Courtenay, W.R., Jr., and J.R. Stauffer, Jr. 1990. The introduced fish problem and the aquarium fish industry. Journal of the World Aquaculture Society 21(3):145-159.

Courtenay, W.R., Jr., D.A. Hensley, J.N. Taylor, and J.A. McCann. 1984. Distribution of exotic fishes in the continental United States. 41-77 in W.R. Courtenay, Jr., and J.R. Stauffer, Jr., eds. Distribution, biology and management of exotic fishes. Johns Hopkins University Press, Baltimore, MD.

Courtenay, W. R., Jr., D. P. Jennings, and J. D. Williams. 1991. Appendix 2: exotic fishes. 97-107 in Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. Common and scientific names of fishes from the United States and Canada, 5th edition. American Fisheries Society Special Publication 20. American Fisheries Society, Bethesda, MD.

Courtenay, W.R., Jr., H.F. Sahlman, W.W. Miley, II, and D.J. Herrema. 1974. Exotic fishes in fresh and brackish waters of Florida. Biological Conservation 6(4):292-302.

Devick, W.S. 1991a. Disturbances and fluctuations in the Wahiawa Reservoir ecosystem. Project F-14-R-15, Job 4, Study I. Division of Aquatic Resources, Hawaii Department of Land and Natural Resources.

Devick, W.S. 1991b. Patterns of introductions of aquatic organisms to Hawaiian freshwater habitats. 189-213 in New directions in research, management and conservation of Hawaiian freshwater stream ecosystems. Proceedings of the 1990 symposium on freshwater stream biology and fisheries management, Division of Aquatic Resources, Hawaii Department of Land and Natural Resources.

Erdsman, D.S. 1984. Exotic fishes in Puerto Rico. 162-176 in W.R. Courtenay, Jr. and J.R. Stauffer, Jr. eds. Distribution, biology, and management of exotic fishes. John Hopkins. Baltimore and London.

Fury, J.R., and F.A. Morello. 1994. The contribution of an exotic fish, the Oscar, to the sport fishery of the Everglades Water Conservation Areas. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 48:474-481.

Gennings, R.M. - Georgia Department of Natural Resources, Atlanta, GA. Response to NBS-G nonindigenous questionnaire.

Hartel, K. E. 1992. Non-native fishes known from Massachusetts freshwaters. Occasional Reports of the Museum of Comparative Zoology, Harvard University, Fish Department, Cambridge, MA.

Hill, J.E. and C.E. Cichra. 2005. Eradication of a reproducing population of convict cichlids, Cichlasoma nigrofasciatum (Cichlidae), in north-central Florida. Florida Scientist 68: 65-74.

Hogg, R. G. 1976a. Ecology of fishes of the family Cichlidae introduced into the fresh waters of Dade County, Florida. Unpublished doctoral dissertation. University of Miami, Coral Gables, FL.

Hogg, R. G. 1976b. Established exotic cichlid fishes in Dade County, Florida. Florida Scientist 39(2):97-103.

Howells, R.G. - Heart of the Hills Research Station, TX Parks and Wildl. Dept., Ingram, TX. Response to NBS-G non-indigenous questionnaire. 1992.

Howells, R.G. 1992. Annotated list of introduced non-native fishes, mollusks, crustaceans and aquatic plants in Texas waters. Texas Parks and Wildlife Department, Management Data Series 78, Austin, TX.

Jackson, D.C. 1999. Flathead catfish: biology, fisheries, and management. American Fisheries Society Symposium. 24:23-36.

Jenkins, R.E., and N.M. Burkhead. 1994. Freshwater fishes of Virginia. American Fisheries Society, Bethesda, MD.

Kent, R. 2000. This fishy story is true. News Journal, Mansfield, OH. August 1.

Kramer, D.L., and M. McClure. 1982. Aquatic surface respiration, a widespread adaptation to hypoxia in tropical freshwater fishes. Environmental Biology of Fishes 7(1):47-55.

Kullander, S.O. - Department of Vertebrate Zoology, Swedish Museum of Natural History, Stockholm, Sweden.

Kullander, S.O. 1986. Cichlid fishes of the Amazon River drainage of Peru. Swedish Museum of Natural History, Stockholm, Sweden.

Lee, D.S., S.P. Platania, and G.H. Burgess. 1983. Atlas of North American freshwater fishes - 1983 supplement. North Carolina Biological Survey and the North Carolina State Museum of Natural History, Raleigh, NC.

Loe, K. 2005. Invasive relocation. Accessed on 02/10/2010.

Loftus, W.F. G. Ellis, M. Zokan, and J. Lorenz. 2004. Inventory of freshwater fish species within the Big Cypress National Preserve: the basis for a long-term sampling program. U.S. Geological Survey Fact Scheet 2004-3131.

Loftus, W.F., and J.A. Kushlan. 1987. Freshwater fishes of southern Florida. Bulletin of the Florida State Museum of Biological Science 31(4):147-344.

Maciolek, J.A. 1984. Exotic fishes in Hawaii and other islands of Oceania. 131-161 in W.R. Courtenay, Jr., and J.R. Stauffer, Jr., eds. Distribution, biology, and management of exotic fishes. The Johns Hopkins University Press, Baltimore, MD.

Morita, C.M. 1981. Freshwater fishing in Hawaii. Division of Aquatic Resources, Department of Land and Natural Resources, Honolulu, HI.

Muusze, B., J. Marcon, G. van den Thillart, V. Almeida-Val. 1998. Hypoxia tolerance of Amazon fish: respirometry and energy metabolism of the cichlid Astronotus ocellatus. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 120(1):151-156.

North American Native Fish Association. 1978. Another threat to natives? The Lateral Line (North American Native Fish Association Newsletter, Semmes, AL), June-July, p. 1.

Page, L.M., and B.M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin Company, Boston, MA.

Ray, J. 1994. Record oscar caught in Okeechobee. Florida Wildlife 48(3):47.

Rivas, L.R. 1965. Florida fresh water fishes and conservation. Quarterly Journal of the Florida Academy of Science 28(3):255-258.

Schainost, S. - Rivers and Streams Program, Nebraska Game and Parks Commission, Lincoln, NE.

Shafland, P.L. and J.M. Pestrak. 1982. Lower lethal temperatures of fourteen non-native fishes in Florida.  Environmental Biology of Fishes 7(2):149-156.

Shima, C.S. 1972. Creel census and fishermen checking station operations, Statewide Dingell-Johns Program. Job Progress Report for Project F-9-2, Job 1 (Study VI). Hawaii Division of Fish and Game, Hawaii.

Southwick, R. - District Fisheries Supervisor, Virginia Department of Game and Inland Fisheries. Richmond, VA. Response to NBS-G non-indigenous questionaire. 1992.

Texas Parks and Wildlife Department. 2001. Fish Records: Water Body - All Tackle. Texas Parks and Wildlife Department. April 24, 2001.

Tilyou, G.A. - Inland Fish Division, Dept. of Wildlife and Fisheries, Baton Rouge, LA. Response to NBS-G nonindigenous questionaire. 1992.

Wakefield, W. - Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ.

Wright, B.R., and J.A. Sorensen. 1995. Feasibility of developing and maintaining a sport fishery in the Salt River Project Canals, Phoenix, Arizona. Technical Report No. 18. Arizona Game and Fish Department, Phoenix, AZ.

Other Resources:
FishBase Summary

Author: Leo Nico, Pam Fuller, and Matt Neilson

Revision Date: 4/18/2013

Peer Review Date: 2/10/2016

Citation Information:
Leo Nico, Pam Fuller, and Matt Neilson, 2018, Astronotus ocellatus (Agassiz in Spix and Agassiz, 1831): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL,, Revision Date: 4/18/2013, Peer Review Date: 2/10/2016, Access Date: 3/22/2018

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Citation information: U.S. Geological Survey. [2018]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [3/22/2018].

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