Species name: Astronotus ocellatus

Common names: oscar, tiger oscar, velvet cichlid, or marble cichlid

Family: Cichlidae

Order: Perciformes

Class: Actinopterygii

Maximum length: 11.8 – 15.7 in ( 30.0 – 40.0 cm)

Minimum tank size: Provide at least 30 gallons of space per Oscar.

Aggressiveness: aggressive. The less aggressive are the Pink Tiger Oscars.

Hardiness: Easy

Distribution: South America. Peru, Colombia, Brazil, and French Guiana. It occurs in the Amazon river basin, along with the Amazonas, Içá, Negro, Solimões, and Ucayali river systems, and also in the Approuague and Oyapock drainages.

Diet: Feeds on small fish, crayfish, worms, and insect larvae. Variety is very important. Will accept flake foods, pellet foods, live foods, bloodworms, earthworms, vegetables such as romaine lettuce, cucumbers, and zucchini. Most experts agree that Oscars should not be fed feeder fish. They are not particularly nutritious and carry a huge risk of disease transmission. You only need to feed your Oscar once a day.

Astronotus ocellatus, also known as Oscar, is a cichlid native to South America. In its natural environment, the Oscar preferably inhabits quiet and shallow slow-moving white-water where it takes shelter under submerged branches.

The Oscars are renowned for their personality and are regarded as one of the most intelligent tropical fish. They are aware of the world outside of their aquarium and will learn to recognize their owner and accept fish food directly from the hand.

Physical Traits

A. ocellatus have been reported to grow to approximately 15 in (34 cm) and can weight up to 1.6 kg (2.6 lbs). Their body is oval shaped. Juveniles are stripped with white and orange wavy bands and have a spotted head while adult have bright orange opercle margins on a chocolate brown background. There is often a black rounded blotch with orange margin at the base of the caudal fin. It has been suggested that these ocelli function to limit fin-nipping by the piranha (Serrasalmus spp.), which co-occur with A. ocellatus in its natural environment. Oscars have the ability to rapidly alter their coloration.

From the original dark and orange form (the tiger oscar), many color forms have been developed through selective breeding: red, blue and albino oscar are some of them.
The oscar is one of the fastest growing fish in the aquarium trade. A healthy specimen can easily gain 1 inch a month for the first 7-8 month of their life.

Tank Requirements

To keep an Oscar healthy, the water should be kept clean. Unfortunately, the Oscar is known for being one of the messiest tropical fishes to keep, so be prepared to perform frequent water changes. Because of its size and messy eating habits, a single oscar fish should be kept in at least 55 gallons. An additional 30 gallon should be provided for each additional oscar kept in the tank. Ideally, Oscars should be kept in groups of 6 or more.

Additionally, the aquarium should have a strong filtration system. When selecting a filter, it is a good idea to chose one that provides filtration in excess of your total aquarium volume.

Water’s temperature should be between 74°F and 81°F. Keeping an Oscar in warmer temperature for an extended period of time can result in oxygen deprivation, which can seriously hamper the immune system and cause nerve damage. Keeping an oscar in colder temperature can also hamper its immune system which makes the fish more susceptible to diseases.

In order to feel comfortable, they need to have lots of hiding places. They will be more active and will come out more often if you can provide plenty of hiding places. Providing sufficient cover reduces stress and therefore improves their immune system, reducing the chance of disease.

Oscars are known to rearrange their tank so if you don’t want them to move everything, the best is to decorate the tank with heavy pieces of wood. Avoid using rough or sharp decorations that the fish may get hurt on. They are very good jumpers, so a heavy hood is a must.

Because they move everything all the time, Oscars are not good candidates for a planted aquarium.

Choosing the tankmates carefully is very important. The Oscar will eat small species so make sure to chose large tankmate. Some of the ideal tankmate for Oscars are the Texas Cichlids, Jack Dempsey and large Plecosomus.

Finally, remember that Oscars are primarily carnivorous. In the wild, Oscars eat small fish, insects, invertebrates, insect larvae and will also consume plant matter. Variety is very important! They will accept flake foods, pellet foods, live foods, bloodworms, earthworms, vegetables such as romaine lettuce, cucumbers, and zucchini.

My name is James, and I’m in love with aquariums and fish since I was 12 years old. Back then my dad gave me a goldfish, and it’s been 35 years learning about this fascinating hobby. I’ve had some freshwater aquariums, tried my hand with marine tanks for 10 years, and kept some reefs for a while too. Here in the website I try to share some of my knowledge and experiences on fish keeping.


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