Oscar Fish: The Wonderful Life of the Oscar Fish

The oscar fish (Astronotus ocellatus) is a fish of the cichlid family, of which there is only another variety, the Astronotus crassipinnis. It is usually known with other vulgar names, such as velvet cichlid, red oscar, tiger oscar fish or marble cichlid. It is a very original fish, which changes its appearance as it ages. When this species is in its juvenile state it is very attractive, with yellow and light brown colors.

While they get less showy when they get older. They are easy to reproduce in captivity, provided they have enough space and are well fed. This species can be taught to perform small tricks, is smart. This breed can eat from the hand of its breeder, and can even be caressed. They respond to the mimes that their owners lavish on them. Being sensitive and also demanding, as if they were part of the family nucleus.

Oscar Fish

Characteristic of Oscar Fish

It is a fish of good size, can measure up to 35 centimeters. They are oval and quite flat, with rounded fins, slightly protruding eyes, largemouth, and strong jaws. Not in vain, everything that moves inside the aquarium that is smaller than him is eaten. In a natural state, the oscar fish is usually dark, with orange ring spots on the caudal peduncle and dorsal fin.

However, in captivity its coloration is “cryptic”, it is composed of irregularly arranged spots and stripes. In young specimens, they are typically black, with white or orange stripes, with spots on their heads. The colorations of the oscar fish bred in captivity are very varied. Going through marbled, speckled, stained colors, with red, black colors, everything of red color or everything of black color.

In specialized stores, it is possible to obtain samples of albino oscar fish. Its coloration can also be changed when it becomes territorial. There are no morphological differences between the male and the female. Although some scholars argue that the male grows faster than the female. And in some natural populations which is difficult to appreciate in the aquarium, the males have black spots at the base of their spine.


The Astronotus ocellatus is a fish native to the Amazon region. It is very present in Latin America. Inhabiting countries such as Colombia, Venezuela, Bolivia, Ecuador, Peru, Brazil, French Guiana, Paraguay, Uruguay, and Argentina. With such a wide geographical distribution, it is not uncommon to find it in numerous river systems, with different habitats. The favorite ones are shallow and calm waters, with white and silty waters. Where it is usually found near tree roots or under vegetal covers.

Aquarium Conditions

The oscar fish needs a good aquarium, that at least has 200/300 liters of water. The temperature of the aquarium should be maintained between 20º and 28ºC. While the pH must be maintained in a range of 6 to 7.5, with a hardness between 90 and 357 ppm. They need well-oxygenated water but do not like too much water movement. So it is convenient to place a couple of oxygen inputs in the tank.

They are fish with a tendency to dig in the substrate, which should be soft and sandy, with some rocks, roots, and large branches of floating wood. These conditions make the aquarium more natural and provide places to hide. It is not recommended to make a decoration very load, rather minimalist, as they are very active.

And everything that the breeder puts on decoration this species will move it and if it is delicate, it will break it. It is recommended to make weekly water changes. In which the breeder change between 30% and 50% of the volume of the aquarium. Another important detail, the water heater of the aquarium, is convenient to place it outside since it is known that some fish have broken the heaters. You may also like to read Plecostomus


It is an omnivorous fish in the broadest sense of the word, it will eat almost anything that you throw into the aquarium. If there are smaller fish, eat them. Its diet is based on insects, crustaceans, zooplankton, and all kinds of vegetables. Although it seems that what he likes most, are fleshy foods, with fruits and other vegetable materials as a preferred option.

The breeder should be provided with a high protein diet, in which the one pill for cichlids should be the fundamental part. And food can be a supplement, with live or frozen foods, worms, prawns, river shrimp, crickets. With these fish, there is a danger of overfeeding because they are very smart and learn to ask their owners for food, whenever they see them approaching the aquarium.


The oscar fish is not aggressive, however, its size and its voracity inhibit it to share an aquarium with other smaller fish. You can look for other cichlids of similar size, with which to share space, although this requires having a large aquarium.


The reproduction of the oscar fish is relatively simple since they are exceptionally prolific, a couple can get up to 1,000 eggs. But, like all reproductions of fish in captivity, they require a series of indispensable requirements. To find a breeding pair, you must start with a group of at least six young fish, which when matured will naturally mate. Fish that do not form pairs are removed from the aquarium. 

The aquarium should have flat rocks or similar structures that provide a good number of spawning sites. During the courtship, the couple will select and clean the place where the spawning will take place. The eggs are white and opaque after laying. Those that are viable, will change color during the first 24 hours.


The oscar fish can be affected by a disease called Hexamita, which causes holes in the head. This disease causes cell necrosis in the muscles of the head. Hexamitiasis is caused by a protozoon called Hexamita, which is in the intestines of animals, which get there ingested with food. Normally they are not a problem unless the fish are subject to stressful situations in the aquarium. Stress is the result of an excessive number of fish, inadequate water quality, sudden changes in temperature, or an inappropriate diet. It can be a serious illness if measures are not taken on time.


Oscar fish is a very popular aquarium fish, but before introducing it into our aquarium we must consider that once adult, it is of a large size, and that it usually lives between 10 and 20 years. At present, there are many ornamental variants of the Astronotus ocellatus, modified to be bred in aquariums and that offer morphological and coloration differences: Tiger oscar, Albino tiger, Red oscar, Veil tail fish, Lutino red oscar, Lemon oscar fish.

We hope this guide has helped you and that your oscar fish is thriving! If not, please get in touch with us. One of our experts would be happy to help diagnose the problem and provide a solution for getting back on track. Good luck with all your future endeavors!

As a Reference: Wikipedia


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