TankBud

One species · 4 varieties

Oscar

Astronotus ocellatus

FreshwaterFish

Oscar (Astronotus ocellatus)

Care at a glance

Temperature
68–82°F
20–28°C
pH
6.0–7.5
Adult size
13.8 in
35 cm
Minimum tank
75 gal
284 L
Temperament
Aggressive
Social behavior
Solitary
Tankmates
With caution
Swim level
Middle
Diet
Carnivore
Difficulty
Medium
Breeding
Substrate spawner · Hard
Rarity
Rare
Family
Cichlidae
Origin
South America

Pick a variety

One setup covers every line on this page: care is the species' care.

Overview

The oscar is a large, intelligent cichlid that cruises the middle of a big tank. It is a fish for keepers past the beginner stage.

Did you know

Oscars are known for their personality and are often called wet pets. They learn to recognize their keeper and can be taught to take food from the hand. They will also follow movement at the front of the tank, which is unusual for a fish.

Caring for the oscar

Plan for at least 75 gal (284 L) for a single adult oscar. It rearranges its tank, so use a sandy floor and secure decor. A few large pieces of driftwood and rounded rocks give it cover. It usually uproots plants, so leave them out or keep them potted and sturdy.

The oscar is adaptable but does best in soft to neutral water. Keep it at 68 to 82°F (20 to 28°C) and a pH of 6.0 to 7.5. It is a heavy eater and a messy fish, so it needs strong filtration and regular large water changes. Make a big volume of clean, well-filtered water the priority, rather than a detailed scape.

Feed a quality cichlid pellet as the staple, with occasional prawn, mussel and earthworm. Avoid a diet of feeder fish or plain mammal meat.

It is usually kept singly or as a bonded pair, in a tank of its own or with big, sturdy tank mates. It is predatory and territorial, and it will swallow any fish small enough to fit in its mouth. It can bully companions, so anything kept with it must be too large to eat and able to hold its own.

It is a substrate spawner. A pair cleans a flat rock, then guards the eggs and fry together. Breeding is hard, mostly because of the fish's size and the difficulty of pairing. Mismatched adults can fight fiercely rather than spawn.

Good to know

The oscar, Astronotus ocellatus, belongs to the cichlid family, Cichlidae, and grows quickly when well fed. It is named for the ocellus, the eye-like orange-ringed spot at the base of the tail. That spot is thought to deflect attacks away from the real eyes.

In the wild

The oscar is widespread across the Amazon and other river systems of tropical South America. It lives in slow, warm waters among submerged wood and roots.

From published sources

Tank mates

Each fish here is named as a tank mate for the oscar by at least two published care guides. Fishkeeping World and Imperial Tropicals recommend keeping it on its own instead. Add tank mates at adult size, since an oscar eats any fish that fits its mouth. The tank needs more than the oscar's own 75 gallons (284 liters).

Sources: Aquarium Co-Op, Fishkeeping World, Aquarium Source, Practical Fishkeeping, Seriously Fish, FishLab.

Check the full mix in the stocking calculator

Common questions

What size tank does an oscar need?

An oscar needs at least 75 gal (284 L). It spends most of its time in the middle.

What temperature and pH does an oscar need?

An oscar is comfortable at 68–82°F (20–28°C) with a pH of 6.0–7.5.

What does an oscar eat?

An oscar eats a quality cichlid pellet as its staple, with prawn, mussel and earthworm now and then. Do not build its diet on feeder fish or plain mammal meat.

How big does an oscar get?

An adult oscar reaches about 13.8 in (35 cm).

How does an oscar breed?

Oscars are substrate spawners, and a pair cleans a flat rock and guards its eggs and fry. Breeding them is hard, because they are big and hard to pair, and mismatched adults may fight instead of spawning.

What fish can live with the oscar?

Published care guides name leopard sailfin pleco, silver dollar, common pleco and silver arowana, among others. Add tank mates at adult size, since an oscar eats any fish that fits its mouth. The tank needs more than the oscar's own 75 gallons (284 liters).

Related species