American Cichlids – Oscar (Astronotus ocellatus)

Updated on November 19, 2020 by

Oscars are very well known for their aggression and territorial behaviour. A correct setup is needed with the right mates to control this aggression. Apart from the aggression, people consider keeping them due to their unique vivid black and cream body with splotches of orange, red and yellow.

Oscars have various patterns of vibrant colours that’ll brighten your tank and the atmosphere around it.

Quick stats – Oscar Cichlid

OriginSouth America
Max size12” / 30 cm
AquariumMin 70 gallon / 280 liters
Water72-77° F / 22-25° C


KH 5-19, pH 6.0-8.0

Care levelDifficult
ColorsBlack, red, orange, albino

Oscars description

Oscars are among the largest aquarium cichlids, showing at times a funny and intelligent behaviour. Their latin name is Astronotus Ocellatus, which was attributed due to their splotches, or “ocelli”, and they’re commonly known as Oscars, Marble cichlid, Tiger Oscar and Velvet cichlid.

Tiger Oscars are a little bit more difficult to care for. The different names are due to its variety of combination of colours and splotches. Oscars like to have sufficient space and have a small society in the aquarium, of about 5-6 Oscars.

The aggression is managed by adding equal numbers of females as the males. Their graceful swim and wonderful colours will captivate any viewer for hours.

They live for about 11 – 13 years in captivity if kept in good health and proper tank maintenance is carried out. Oscars are quite popular in the aquarium trade industry so they are available in aquarium stores at about $10.

Oscars are a species of cichlids so basically belong to the American Cichlidae family. Males are relatively larger in size than females. They should be provided with a sufficiently large tank, of about 55 gallons per Oscar. This way they can grow to their maximum captivity size of 12 inches, otherwise not provided with a suitable tank, they will suffer from dwarfism.

It is quite difficult to distinguish males and female Oscars but it has been observed that males are larger in size, darker in colour, show more aggression and have 3 dark spots at the base of their dorsal fin. Looking more closely at the genitals of Oscars, females have oviduct just prior to or during spawning.

Oscar Cichlid in the natural habitat

This tropical freshwater fish is naturally found in the wildlings of the Amazon river. Through the collective breeding by the aquarium industry it’s readily available in stores to make your aquarium look fabulous.

So, Oscars favour a warm and neutral pH water – they can’t tolerate acidity or alkalinity. The river has an active vegetation at the bottom so the same should be mimicked in captivity: rocks, debris and some plants for the perfect health of the Oscars.

The light condition should be sufficient enough to penetrate the water surface and reach the bottom of the tank, just like their natural habitat.

Oscars live in the lowest turbidity areas of the natural river habitat. Therefore, a clean and highly oxygenated, and very well filtered freshwater should be provided. The ammonia levels should be always kept at the lowest levels, because the water of the river is always flowing.

To maintain the best condition of the tank, these parameters are to be neatly monitored and regulated.

Oscars in the ideal aquarium

Oscar - Astronotus ocellatus
Oscar - Astronotus ocellatus
Oscar - Astronotus ocellatus
Oscar - Astronotus ocellatus
Oscar - Astronotus ocellatus

Oscars need lots of area to grow properly or else they suffer dwarfism. Therefore, a minimum 55 gallons tank is recommended for one Oscar; at least 30-40 gallons of water should be added furthermore per every Oscar introduced.

Don’t overcrowd the tank or territory disputes are likely to occur. Smaller tanks make Oscars ill or more aggressive so a huge tank, with very well filtered water is very essential.

As the natural habitat of Oscars is neutral pH freshwater, the tanks’ pH levels of freshwater should be between 6 to 8. The temperature of the water should be maintained around 24 to 28 degrees Celsius; total hardness to be under 15-degree dGH.

These parameters are easy to maintain by using pH meters, thermometers, and hardness checkers, etc. Moreover, monitoring should be done once in a blue moon because a heavy-duty filter is more than enough to maintain hardness, pH, and ammonia levels. For temperature control, a heater will be ideal.

To maintain the oxygen level, an air pump should be used, but not a very strong one, as the water should be slowly moving around the tank. The adequate light conditions must be provided – it should be strong enough to reach the aquarium’s bottom. Led lights should be the best, as they don’t heat much.

The base of the tanks should be layered with soft substrate, fine grained red sand being the right choice for Oscars because they like to dig and even lay eggs there; hard substrate will scratch their bodies.

Huge round pebbles can be used as protection to the live plants and used as decorations. Also, when picking decorations, one should be careful as the Oscars like moving things around, and that could potentially damage the tank.

Some hidden spots should be provided so that the younger can hide if the dominant ones become aggressive. These hiding spots are also useful at the time of breeding where the females lay eggs. The decoration should be minimal because Oscars like to swim freely in space.

Selecting the plants is also vital as Oscars love digging and during aggression, they can cause irreversible damage to the plants. Therefore, hard plants should be considered like hornworts, beefy plants, floating plants or any other deeply rooted plants. Oscars love plants and are expected to eat them at times, so choose them wisely.

As described earlier, Oscars are quite territorial and aggressive species, so don’t associate them with any other territorial fish. Avoid putting small fish or they will end up as snacks for the omnivorous Oscars.

You can for instance add Firemouth Cichlids, or large Plecos into the tanks as they are compatible with Oscars.

Oscar Cichlid feeding

In the wild, Oscars feed on little fishes, larvae, small plant debris, but also small insects and crustaceans are vital part of their diet. So, you can include live or frozen foods which are rich in protein like bloodworms, earthworms, brine shrimp or daphnia, etc into their daily diet.

Live food even encourages Oscars to bring out natural hunting traits.

Home chopped leafy greens are also acceptable. Homemade diet should include all the nutrients for growth and health.

There is special food for Cichlids available in the stores with all the nutrients for their growth and health but if you are planning for a really huge tank then that might hurt your budget. Among the best food for Cichlids we recommend: Hikari Cichlid Gold Floating Pellets Large.

Feed Oscars several times a day and try to spread the food in a few places, otherwise disputes might take place.

It is not recommended to give them red fish or chicken. Keep also in mind not to overfeed your Oscars. They aren’t picky eaters so they will eat everything that’s offered. That’s why overfeeding has to be avoided at all costs, as it may lead to various health complications including constipation.

Oscar Cichlid breeding

For successful breeding, it is important to keep pairs of youngers together and let them reach sexual maturity. The mature fish is about 5 inches long. They make pairs on their own. The tank should have flatbed spaces for the choice of spawning site.

Naturally the fish breeds in the rainy season but the spawning season takes place just before the rainy season too. There are few indications that the Oscars are ready for breeding when they start digging large holes and clean them.

During breeding, the males show quite aggressive behavior. Note that breeding can’t be carried out in community tanks as fry can be eaten by other fish. Sometimes, even separating the couple can lead to effective and successful breeding.

You should adjust the temperature in the range of 26 to 28 degree Celsius during the Oscars spawning. The fish lay about 500 to 2500 eggs in the flatbed. After about 3-4 days, the fry begin to hatch.

The parents are quite protective of the fry and don’t hesitate to attack other fish nearby their territory. About a week or so the fry start to swim close to their parents. Fry tend to grow quickly to about 2 inch, and further growth becomes slower.

Fry can further be separated from the tank for growing in a safe environment.

The food for these little Oscars is infusoria, young daphnia or dry foods. Nutritional foods are available in aquarium stores for fry.

To conclude

From setting up the tank to feeding the Oscars, seems like an effort but we assure you, it’s not. This little effort will reward you with unique social behaviors like watching you during tank maintenance, recognizing the person who takes care of them, and being curious at times.

The personal satisfaction of just watching the Oscars swim swiftly and gracefully across the free middle space of the aquarium just brightens any mood. The colors and patterns of the Oscar Cichlids are so eye-catching and mesmerizing.

Moreover, they eat anything you feed them so be careful when choosing their tank mates and keep an eye on their diet, as overfeeding is to be highly avoided.

We assure you, that’ll love your Oscars!

Oscar Cichlid FAQs

How quickly do Oscar Cichlids grow?

They grow quite quickly; you can assume 1 inch per month. They reach 12 inches optimally.

What are the diseases associated with Oscar Cichlids?

Head disease where they get a hole in the head, hexamita and stringy feces. These are quite common and mostly recover with the right food and nutrition. But isolation is commonly preferred.

How often do Oscar Cichlids breed?

Oscars breed once a year, mostly in the rainy season.

What are Oscar Cichlid compatible tank mates?

You can add a few species but check for compatibility first. Common mates are large Plecos, Firemouth Cichlids.

How long do Oscar Cichlids live?

Typically, Oscar Cichlids live for about 8-12 years but with good care they can live even longer.