Oscar fish

Introduction:

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. It is considered a popularaquarium fish in the U.S

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'.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 (18 in) in length and 1.6 kilograms (3.5 lb) in weigh.Although the species is widely regarded as sexually monomorphic 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 is 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 geophaginecichlids. 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.

Feeding and selective breeding:
Captive oscars may be fed prepared fish food designed for large carnivorous fish, crayfish, worms, and insects (such as flies, crickets and grasshoppers). Feeding live foods may increase the rate of growth but also may cause endoparasites. Poultry and/or mammalian flesh, including beefheart, should not be fed long term as these fatty foods will contribute to fatty liver disease. Since these fish eat fruit in the wild, items such as melons, oranges, and other fruits can also be used as a type of food. Just about anything that falls 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. These contain an enzyme (thiaminase) 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.