How big does Oscar get?

Oscar reaches an adult standard length of 25–35 cm (excluding the caudal fin). Size the tank for that, not for the juvenile you bring home — the difference is often several times over, and upgrading later costs more than buying once.

What water does Oscar need?

23–28 °C, pH 6–7.5, 3–15 dGH. At 5 °C wide it is one of the more forgiving ranges.

What is the smallest tank for Oscar?

At least 300 L, and no shorter than 120 cm. That is the floor for long-term keeping, not for short-term survival: volume buys water stability and length buys swimming room, and neither substitutes for the other. It is not a schooling fish, so a single specimen or a pair is fine.

What is Oscar like to keep?

Temperament: predator. Difficulty: moderate. It occupies the middle and is carnivore. With plants it is "Eats plants".

Can Oscar be kept with its most common tank mate?

The checker returns "Not recommended together". Oscar and Guppy is a recorded conflict in this atlas. Predation, territorial fighting or conspecific aggression is the usual outcome, and a bigger tank does not change it.

G-01 / 26Freshwater

Oscar地图鱼

Astronotus ocellatus · Cichlidae

A big, personable cichlid that needs a 120 cm tank alone and treats any fish fitting its mouth as food.

Illustration to come

G-01 / 26 · Oscar Astronotus ocellatus

SpecificationsFish atlas

Name: 地图鱼
Scientific name: Astronotus ocellatus
Family: Cichlidae
Origin: Amazon basin, South America (Brazil, Colombia, Peru)
Adult size: 25–35 cm
Temperament: Predator
Diet: Carnivore
Water level: Middle
Level: Moderate
Min. tank: 300 L
Min. length: 120 cm
Plant safe: Eats plants

Water requirementsFreshwater

Temp.23–28 °C

pH6–7.5

Hardness3–15 dGH

Units: temperature in °C, hardness in German degrees (dGH / dKH), marine salinity as specific gravity at 25 °C, volume in litres. These are the values recorded for the species and do not follow the site unit switcher.

Keeping notes

1Adults pass 30 cm, so one fish needs a 120 cm, 300 L tank with heavy filtration.
2A committed predator: any fish that fits its mouth becomes food, tetras and corydoras included.
3Rearranges substrate, uproots plants and topples decor, so use rock and wood instead.
4Carnivorous on pellets, prawn and fish chunks, with a heavy bioload, so change 30 % or more weekly.
5Tankmates must be too large to swallow, such as silver dollars or big plecos, and the tank must be sized for adults.

Check a tank mate

Jump straight to the verdict for Oscar against this one — no need to pick it again.

Frequently asked questions

How big does Oscar get?: Oscar reaches an adult standard length of 25–35 cm (excluding the caudal fin). Size the tank for that, not for the juvenile you bring home — the difference is often several times over, and upgrading later costs more than buying once.
What water does Oscar need?: 23–28 °C, pH 6–7.5, 3–15 dGH. At 5 °C wide it is one of the more forgiving ranges.
What is the smallest tank for Oscar?: At least 300 L, and no shorter than 120 cm. That is the floor for long-term keeping, not for short-term survival: volume buys water stability and length buys swimming room, and neither substitutes for the other. It is not a schooling fish, so a single specimen or a pair is fine.
What is Oscar like to keep?: Temperament: predator. Difficulty: moderate. It occupies the middle and is carnivore. With plants it is "Eats plants".
Can Oscar be kept with its most common tank mate?: The checker returns "Not recommended together". Oscar and Guppy is a recorded conflict in this atlas. Predation, territorial fighting or conspecific aggression is the usual outcome, and a bigger tank does not change it.