Hot Water Fish

Oscar Fish

  • Scientific name: Astronotus ocellatus, acara ocellatus
  • Common name: Oscar fish, tiger oscar fish
  • Aquarium size: 200 to 300 liters
  • Temperament: Calm
  • Temperature:  Between 20º and 28ºC
  • pH: Between 6 and 7.5
  • Diet: Omnivores
  • Length: 35 cms



The oscar fish, astronotus ocellatus , is a fish of the cichlid family , of which there is only one other variety, the astronotus crassipinnis.
It is usually known by other common 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 , being very attractive in its youthful state, with yellow and light brown colors, while when they age they are less showy.
They are easy to reproduce in captivity, provided they have enough space and are well fed.
It is said that they can be taught to perform little tricks,it is intelligent, it can eat from our hand, and it can even be stroked. They respond to the pampering that their owners lavish on them, being sensitive and also demanding, as if they were part of the family nucleus.


It is a good size fish, it can measure up to 35 centimeters. They are oval in shape and fairly flat, with rounded fins, slightly bulging eyes, a large mouth, and strong jaws. Not surprisingly, he eats everything that moves inside the aquarium that is smaller than him.
In its natural state, oscarfish are usually dark, with orange-ringed spots on the caudal peduncle and dorsal fin.
However, in captivity its coloration is «cryptic», it is composed of irregularly arranged spots and stripes, which in young specimens are typically black, with white or orange stripes, with dots on their heads.
The colorations of the oscar fish raised in captivity are very varied,going through marbled, speckled, stained colors, with red, black, all red or all black. In specialized stores, it is possible to get albino oscar fish.
Its coloration can also be changed when it becomes territorial.
Morphological differences are not distinguished between the male and the female, although some scholars argue that the male grows faster than the female, and that in some natural populations (difficult to appreciate in the aquarium), males have black spots at the base of your spine.

Distribution and habitat

The astronotus ocellatus is a fish native to the Amazon region , being present in Colombia, Venezuela, Bolivia, Ecuador, Peru, Brazil, French Guiana, Paraguay, Uruguay and Argentina.
With such a wide geographic distribution, it is not uncommon for it to have been found 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 plant covers.

Ideas for setting up your aquarium

  • Best complete aquariums
  • Best Small Aquarium
  • Best external filters for aquarium
  • Best aquarium heater
  • Best Aquarium Oxygenator
  • Best Aquarium LED Display
  • Better sand
  • Best substrate for aquarium
  • Best compost for plants
  • Best Aquarium Stones
  • Best aquarium logs
  • Best Aquarius Test
  • Best Ph meter 
  • Best fish food
  • Best Fish Food Dispenser

Aquarium conditions

The oscar fish needs a good aquarium , which has at least 200/300 liters of water, in which the temperature is kept between 20º and 28ºC. 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 they don’t like too much movement of the water, so it is convenient to place a couple of oxygen inlets in the tank.
They are fish with a tendency to burrow into the substrate , which should be soft and sandy, with some rocks, roots and large branches of floating wood, to give it more naturalness, and provide them with places to hide.
It is not recommended to make a very loaded decoration, rather minimalist, sinceThey are very active and everything you put as decoration will move it and if it is delicate, they will break it.
It is recommended to make weekly water changes, in which between 30% and 50% of the aquarium volume is changed.
Another important detail, the aquarium water heater, should be located outside, as some fish are known to have broken the heaters. If we cannot, they must be fixed well hidden by a stone that is difficult to move, so that they cannot access.


It is an omnivorous fish in the broadest sense of the word, it will eat almost anything you put in the aquarium.
If there are smaller fish, it eats them. Insects, crustaceans, zooplankton, all kinds of vegetables … although it seems that what he likes the most, are meaty foods, with fruits and other plant materials as the preferred option.
A high protein diet should be provided , in which a cichlid pill should be the fundamental part and complement it, with live or frozen foods, worms, prawns, river shrimp, crickets.
With these fish there is a danger of overfeeding, because they are very clever and learn to ask their owners for food, every time they see them approach the aquarium.

Behavior and compatibility

The oscar fish is not aggressive, however, its size and voracity inhibit it from sharing the 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.

Fish compatible with Oscar fish

They are supported without restrictions:

  • Common Pleco Fish, as long as it does not fit in the Oscar’s mouth
  • Striped Rafaelo Fish
  • Pleco Galaxy

The following varieties of fish can coexist under restrictions , such as being known from a young age:

  • Flower horn
  • Green Horror Fish
  • Jack Dempsey Fish
  • King Fish Midas
  • Pangasius shark, if similar in size
  • Koi carp , if similar in size

There are others that could coexist, depending on the Oscar’s personality, such as the Ancistrus , the Apple Snail or the Red Piranha .


The reproduction of the oscar fish is relatively simple, since they are exceptionally prolific, a couple can lay up to 1,000 eggs.
But, like all captive fish reproductions, they require a series of indispensable requirements.

  • To find a breeding pair, you should start with a group of at least six young fish, which upon reaching sexual maturity will mate naturally.
  • Fish that do not form pairs are removed from the aquarium.
  • The aquarium should have flat rocks or similar structures, which provide them with a good number of places to spawn.
  • During courtship, the pair will select and clean the spawning site.
  • The eggs are white and opaque after laying. Those that are viable will change color during the first 24 hours.
  • The adults tend to care for the fry even after hatching, but once they swim by themselves, they can be separated.

Be aware that this fish grows a lot and is also very prolific. In some places it is considered an invasive pest, because many of the aquarium fish when they grow, are released and continue to reproduce in the wild.


It is a very popular aquarium fish, but before introducing it into our aquarium we must consider that once it is adult, it is of a large size, and that it usually lives between 10 and 20 years.
Currently, there are many ornamental variants of the astronotus ocellatus, modified to be reared in aquariums and that offer morphological and coloration differences: tiger oscar fish, albino tiger oscar fish, red oscar fish, veiltail oscar fish, Lutino red oscar fish , lemon oscar fish …

Oscar fish diseases

Oscarfish can be affected by a disease called Hexamite , which causes holes in the head. This disease causes cell necrosis in the muscles of the head.
Hexamitiasis is caused by a protozoan called Hexamite, which is in the intestines of animals, which arrive there ingested with food.
They are usually not a problem, unless the fish are subjected to stressful situations in the aquarium, as a result of an excessive number of fish, an inadequate water quality, sudden changes in temperature or an inappropriate diet.
It can be a serious illness, if measures are not taken in time.

Photos of the Oscar Fish

Publicaciones relacionadas

Deja una respuesta

Tu dirección de correo electrónico no será publicada. Los campos obligatorios están marcados con *

Mira también
Botón volver arriba