Astronotus ocellatus
Encyclopedia
Astronotus ocellatus is a species of fish
from the cichlid
family
known under a variety of common names, including oscar, tiger oscar, velvet cichlid, or marble cichlid. In 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 can also be found in other areas, including China, Australia, and the United States. Although its slow growth limits its potential for aquaculture
, it is considered a popular aquarium
fish.
in 1831 as Lobotes ocellatus, as he mistakenly believed the species was marine; later work assigned the species to the genus Astronotus. The species also has a number of junior synonyms: Acara compressus, Acara hyposticta, Astronotus ocellatus zebra, and Astronotus orbiculatus.
. 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. The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics. Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.
, Ecuador
, Colombia
, Brazil
, and French Guiana
, and occurs in the Amazon river basin, along the Amazonas, Içá
, Negro, Solimões
, and Ucayali
river systems, and also in the Approuague
and Oyapock
drainages. In its natural environment, the species typically occurs in slow-moving white-water habitats, and has been observed sheltering under submerged branches. Feral populations also occur in China
, northern Australia
, and Florida, USA
as a by-product 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 (55.2 °F).
, males have been suggested to grow more quickly, and in some naturally occurring strains, males are noted to possess dark blotches on the base of the dorsal fin. The species reaches sexual maturity at approximately one year of age, and continues to reproduce for nine to ten years. Frequency and timing of spawning may be related to the occurrence of rain. A. ocellatus fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild are scarce.
The closely related Astronotus crassipinnis has been observed, in times of danger, to store food in its mouth, possibly for protection, in a manner reminiscent of mouthbrooding geophagine
cichlids. This behaviour, however, has not yet been observed in A. ocellatus. 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. Like most cichlids, A. ocellatus practices brood care, although the duration of brood care in the wild remains unknown.
, worms, and insects such as flies
or grasshopper
s. They even eat small mice, and crickets are also good live food. Since these fish eat fruit in the wild, it can also be used as a type of food. Just about anything that fell into the water would be eaten by oscars. Live feeder fish can be given, but fish such as goldfish and rosy red feeder minnows should not be fed. They also contain an enzyme within their flesh which binds vitamin B1, leading to deficiency. 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, and has been reported to exhibit "laying-on-side" death mimicry in a similar fashion to Parachromis friedrichsthalii and Nimbochromis livingstonii
. The species also has an absolute requirement for vitamin C
, and develops health problems in its absence.
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. 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". In recent years long-finned varieties have also been developed. The species is also occasionally artificially coloured by a process known as painting
.
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
from the cichlid
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
known under a variety of common names, including oscar, tiger oscar, velvet cichlid, or marble cichlid. In South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, where the species naturally resides, A. ocellatus specimens are often found for sale as a food fish in the local markets. The fish can also be found in other areas, including China, Australia, and the United States. Although its slow growth limits its potential for aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
, it is considered a popular aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
fish.
Taxonomy
The species was originally described by Louis AgassizLouis Agassiz
Jean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...
in 1831 as Lobotes ocellatus, as he mistakenly believed the species was marine; later work assigned the species to the genus Astronotus. The species also has a number of junior synonyms: Acara compressus, Acara hyposticta, Astronotus ocellatus zebra, and Astronotus orbiculatus.
Description
A. ocellatus examples have been reported to grow to about 45 cm (17.7 in) in length and 1.6 kilograms (3.5 lb) in weight. The wild-caught forms of the species are typically darkly coloured with orange-ringed spots or ocelli on the caudal peduncle and on the dorsal finDorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
. These ocelli have been suggested to function to limit fin-nipping by piranha
Piranha
A piranha or piraña is a member of family Characidae in order Characiformes, an omnivorous freshwater fish that inhabits South American rivers. In Venezuela, they are called caribes...
(Serrasalmus
Serrasalmus
The genus Serrasalmus consists of several species of piranhas in family Serrasalmidae of the family Characidae. They are collectively known as pirambebas; the "typical" piranhas like the Piraya Piranha are nowadays placed in Pygocentrus....
spp.), which co-occur with A. ocellatus in its natural environment. The species is also able to rapidly alter its colouration, a trait which facilitates ritualised territorial and combat behaviours amongst conspecifics. Juvenile oscars have a different colouration from adults, and are striped with white and orange wavy bands and have spotted heads.
Distribution and habitat
A. ocellatus is native to PeruPeru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, and French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
, and occurs in the Amazon river basin, along the Amazonas, Içá
ICA
- Business :* Empresas ICA , large construction company in Mexico* ICA AB, a Swedish corporate group in the food retail business, formerly named ICA Ahold AB....
, Negro, Solimões
Solimões
Solimões is the name often given to early stretches of the Amazon River from the border of Brazil and Peru to its confluence with the Rio Negro.Further upstream from the border, the name of the river seems to depend on the speaker...
, and Ucayali
Ucayali
The Ucayali River arises about north of Lake Titicaca, in the Arequipa region of South America. The Amazon River takes its name close to Nauta city , in the confluence among Ucayali and Marañón rivers....
river systems, and also in the Approuague
Approuague River
The Approuague river is a major river in French Guiana. Itruns north from the Tumuk Humak Mountains to the Atlantic Ocean, almost parallel with the Oiapoque, with its mouth in Pointe Béhague or Cumarumã....
and Oyapock
Oyapock River
The Oyapock or Oiapoque River is a 370-km long river in South America that forms most of the border between French Guiana and the Brazilian state of Amapá...
drainages. In its natural environment, the species typically occurs in slow-moving white-water habitats, and has been observed sheltering under submerged branches. Feral populations also occur in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, northern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, and Florida, USA
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
as a by-product 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 (55.2 °F).
Sexual dimorphism
Although the species is widely regarded as sexually monomorphicSexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, males have been suggested to grow more quickly, and in some naturally occurring strains, males are noted to possess dark blotches on the base of the dorsal fin. The species reaches sexual maturity at approximately one year of age, and continues to reproduce for nine to ten years. Frequency and timing of spawning may be related to the occurrence of rain. A. ocellatus fish are biparental substrate spawners, though detailed information regarding their reproduction in the wild are scarce.
The closely related Astronotus crassipinnis has been observed, in times of danger, to store food in its mouth, possibly for protection, in a manner reminiscent of mouthbrooding geophagine
Geophagus
Geophagus is a genus of cichlids from South America. The genus is currently polyphyletic and in need of further taxonomic revision. Some geophagine cichlids previously included in this genus have been reallocated to Gymnogeophagus or Satanoperca...
cichlids. This behaviour, however, has not yet been observed in A. ocellatus. 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. Like most cichlids, A. ocellatus practices brood care, although the duration of brood care in the wild remains unknown.
Feeding
Captive oscars may be fed prepared fish food designed for large carnivorous fish, crayfishCrayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
, worms, and insects such as flies
Fließ
Fließ is a municipality in the Landeck district and is located5 km south of Landeck on the upper course of the Inn River. It has 9 hamlets and was already populated at the roman age; the village itself was founded around the 6th century. After a conflagration in 1933 Fließ was restored more...
or grasshopper
Grasshopper
The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...
s. They even eat small mice, and crickets are also good live food. Since these fish eat fruit in the wild, it can also be used as a type of food. Just about anything that fell into the water would be eaten by oscars. Live feeder fish can be given, but fish such as goldfish and rosy red feeder minnows should not be fed. They also contain an enzyme within their flesh which binds vitamin B1, leading to deficiency. Most fish eaten by A. ocellatus in the wild are relatively sedentary catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
, including Bunocephalus
Bunocephalus
Bunocephalus is a genus of catfishes of the family Aspredinidae. Currently not a natural grouping, Bunocephalus contains species of an undescribed genus Pseudobunocephalus. B...
, Rineloricaria
Rineloricaria
Rineloricaria is a genus of freshwater tropical catfish belonging to the Loricariidae family. They are commonly called whiptail catfish because of the long filament that grows out of the tip of the caudal fin that is characteristic of the genus...
, and Ochmacanthus
Ochmacanthus
Ochmacanthus is a genus of catfishes of the family Trichomycteridae. It includes five species, O. alternus, O. batrachostoma, O. flabelliferus, O. orinoco, and O. reinhardtii. Ochmacanthus species are distributed in South America. O. alternus and O...
species. The species uses a suction mechanism to capture prey, and has been reported to exhibit "laying-on-side" death mimicry in a similar fashion to Parachromis friedrichsthalii and Nimbochromis livingstonii
Nimbochromis livingstonii
Nimbochromis livingstonii, Livingston's Cichlid or kalingono, is a freshwater mouthbrooding cichlid fish of the genus Nimbochromis, native to Lake Malawi, an African Rift Lake. It is also found in the upper Shire River and Lake Malombe...
. The species also has an absolute requirement for vitamin C
Vitamin C
Vitamin C or L-ascorbic acid or L-ascorbate is an essential nutrient for humans and certain other animal species. In living organisms ascorbate acts as an antioxidant by protecting the body against oxidative stress...
, and develops health problems in its absence.
Selective breeding
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
industry. These include forms with greater intensity and quantities of red marbling across the body, albino, leucistic, and xanthistic
Xanthochromism
Xanthochromism is a term that may be applied to birds, fish and other animals whose colouration is unusually yellow through an excess of yellow pigment, or possibly a loss of darker pigments that allows yellow pigment to be unusually dominant...
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. 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". In recent years long-finned varieties have also been developed. The species is also occasionally artificially coloured by a process known as painting
Painted fish
The term painted fish refers to ornamental aquarium fish which have been artificially coloured to appeal to consumers. This artificial colouring, also known as juicing, is achieved by a number of methods, such as injecting the fish with a hypodermic syringe containing bright fluorescent colour dye,...
.