Species › Cichlids

Oscar tank mates and minimum tank size

Astronotus ocellatus

Oscars grow to 46 cm (18 in). They eat any fish small enough to swallow. They need 22–25 °C (72–77 °F) and pH 6.0–7.5.

Minimum tank

540 L (143 US gal), at least 150 cm (59 in) long

Adult size

46 cm (18 in)

Temperature

22–25 °C (72–77 °F)

pH

pH 6.0–7.5

Group

no minimum

Oscar minimum tank size

Oscars need at least 540 L (143 US gal), in a tank at least 150 cm (59 in) long.

That is the largest minimum among the sources below. The planner also checks the tank length against the adult size of 46 cm (18 in): a tank shorter than 4 times that is cramped (183 cm (72 in)).

Oscar tank mates

Each of the other 52 species in this reference, judged against oscars by the same rules as the compatibility checker. A guide, not a guarantee.

Compatible (1)

• Common pleco

With care (1)

• Clown loachThe only temperature that suits both is 25 °C (77 °F), set by clown loaches and oscars. That leaves no margin.

Not compatible (50)

• AngelfishAngelfish need 25.6–28.9 °C (78–84 °F); oscars need 22–25 °C (72–77 °F). No temperature suits both. Oscars grow to 46 cm and eat animals they can swallow; angelfish grow to 15 cm.
• BettaOscars grow to 46 cm and eat animals they can swallow; bettas grow to 7 cm. The only temperature that suits both is 24.4–25 °C (76–77 °F), set by bettas and oscars. That leaves no margin. Bettas are usually best kept alone. Some accept calm tank mates such as oscars, many do not.
• Black neon tetraOscars grow to 46 cm and eat animals they can swallow; black neon tetras grow to 3.5 cm.
• Black skirt tetraOscars grow to 46 cm and eat animals they can swallow; black skirt tetras grow to 7.5 cm.
• Boeseman's rainbowfishBoeseman's rainbowfish need 27–30 °C (81–86 °F); oscars need 22–25 °C (72–77 °F). No temperature suits both. Oscars grow to 46 cm and eat animals they can swallow; Boeseman's rainbowfish grow to 11 cm.
• Bristlenose plecoOscars grow to 46 cm and eat animals they can swallow; bristlenose plecos grow to 15 cm.
• Bronze corydorasOscars grow to 46 cm and eat animals they can swallow; bronze corydoras grow to 7.5 cm. The only temperature that suits both is 25 °C (77 °F), set by bronze corydoras and oscars. That leaves no margin.
• Cardinal tetraOscars grow to 46 cm and eat animals they can swallow; cardinal tetras grow to 3.5 cm. The only pH that suits both is pH 6.0, set by oscars and cardinal tetras. That leaves no margin.
• Celestial pearl danioOscars grow to 46 cm and eat animals they can swallow; celestial pearl danios grow to 2.1 cm. Celestial pearl danios (2.1 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Cherry barbOscars grow to 46 cm and eat animals they can swallow; cherry barbs grow to 5 cm.
• Cherry shrimpOscars grow to 46 cm and eat animals they can swallow; cherry shrimp grow to 4 cm.
• Chili rasboraOscars grow to 46 cm and eat animals they can swallow; chili rasboras grow to 3.5 cm. The only temperature that suits both is 25 °C (77 °F), set by chili rasboras and oscars. That leaves no margin. Chili rasboras (3.5 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Cockatoo dwarf cichlidOscars grow to 46 cm and eat animals they can swallow; cockatoo dwarf cichlids grow to 7.5 cm. The only pH that suits both is pH 6.0, set by oscars and cockatoo dwarf cichlids. That leaves no margin. Cockatoo dwarf cichlids fight other cichlids, and oscars are one of them.
• Congo tetraOscars grow to 46 cm and eat animals they can swallow; Congo tetras grow to 8 cm. Congo tetras (8 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Convict cichlidOscars grow to 46 cm and eat animals they can swallow; convict cichlids grow to 15 cm. Convict cichlids are aggressive and best kept in a tank of their own; they attack fish several times their size, so oscars would be harassed.
• DiscusDiscus need 26–30 °C (79–86 °F); oscars need 22–25 °C (72–77 °F). No temperature suits both. Oscars grow to 46 cm and eat animals they can swallow; discus grow to 14 cm.
• Dwarf gouramiOscars grow to 46 cm and eat animals they can swallow; dwarf gouramis grow to 9.5 cm. The only temperature that suits both is 25 °C (77 °F), set by dwarf gouramis and oscars. That leaves no margin.
• Ember tetraOscars grow to 46 cm and eat animals they can swallow; ember tetras grow to 2 cm. Ember tetras (2 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Endler's livebearerOscars grow to 46 cm and eat animals they can swallow; Endler's livebearers grow to 2.5 cm. Endler's livebearers (2.5 cm) are shy and easily intimidated by much larger oscars (46 cm).
• German blue ramGerman blue rams need 27–30 °C (81–86 °F); oscars need 22–25 °C (72–77 °F). No temperature suits both. Oscars grow to 46 cm and eat animals they can swallow; German blue rams grow to 4.2 cm. The only pH that suits both is pH 6.0, set by oscars and German blue rams. That leaves no margin. German blue rams (4.2 cm) are shy and easily intimidated by much larger oscars (46 cm). German blue rams fight other cichlids, and oscars are one of them.
• Glass catfishOscars grow to 46 cm and eat animals they can swallow; glass catfish grow to 6.5 cm. Glass catfish (6.5 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Glowlight tetraOscars grow to 46 cm and eat animals they can swallow; glowlight tetras grow to 4 cm.
• GoldfishOscars need 22–25 °C (72–77 °F); goldfish need 15.6–21.1 °C (60–70 °F). No temperature suits both.
• GuppyOscars grow to 46 cm and eat animals they can swallow; guppies grow to 6 cm.
• Harlequin rasboraOscars grow to 46 cm and eat animals they can swallow; harlequin rasboras grow to 5 cm.
• Honey gouramiOscars grow to 46 cm and eat animals they can swallow; honey gouramis grow to 14 cm. Honey gouramis (14 cm) are shy and easily intimidated by much larger oscars (46 cm).
• KribensisOscars grow to 46 cm and eat animals they can swallow; kribensis grow to 11 cm. Kribensis (11 cm) are shy and easily intimidated by much larger oscars (46 cm). Kribensis fight other cichlids, and oscars are one of them.
• Kuhli loachOscars grow to 46 cm and eat animals they can swallow; kuhli loaches grow to 12 cm.
• Lemon tetraOscars grow to 46 cm and eat animals they can swallow; lemon tetras grow to 4 cm.
• MollyOscars grow to 46 cm and eat animals they can swallow; mollies grow to 8 cm. The only pH that suits both is pH 7.5, set by mollies and oscars. That leaves no margin.
• Mystery snailOscars eat snails, mystery snails included. The only pH that suits both is pH 7.2–7.5, set by mystery snails and oscars. That leaves no margin.
• Neon tetraOscars grow to 46 cm and eat animals they can swallow; neon tetras grow to 3 cm.
• Nerite snailOscars eat snails, nerite snails included.
• OtocinclusOscars grow to 46 cm and eat animals they can swallow; otocinclus grow to 5 cm. Otocinclus (5 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Panda corydorasOscars grow to 46 cm and eat animals they can swallow; panda corydoras grow to 5 cm.
• Paradise fishOscars grow to 46 cm and eat animals they can swallow; paradise fish grow to 8 cm. The only temperature that suits both is 22 °C (72 °F), set by oscars and paradise fish. That leaves no margin.
• Pearl gouramiOscars grow to 46 cm and eat animals they can swallow; pearl gouramis grow to 12 cm. Pearl gouramis (12 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Peppered corydorasOscars grow to 46 cm and eat animals they can swallow; peppered corydoras grow to 7 cm.
• PlatyOscars grow to 46 cm and eat animals they can swallow; platies grow to 5 cm.
• Pygmy corydorasOscars grow to 46 cm and eat animals they can swallow; pygmy corydoras grow to 3 cm. Pygmy corydoras (3 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Red tail sharkOscars grow to 46 cm and eat animals they can swallow; red tail sharks grow to 13 cm.
• Rosy barbOscars grow to 46 cm and eat animals they can swallow; rosy barbs grow to 14 cm. The only temperature that suits both is 22 °C (72 °F), set by oscars and rosy barbs. That leaves no margin.
• Rummy-nose tetraOscars grow to 46 cm and eat animals they can swallow; rummy-nose tetras grow to 5 cm. The only pH that suits both is pH 6.0, set by oscars and rummy-nose tetras. That leaves no margin. Rummy-nose tetras (5 cm) are shy and easily intimidated by much larger oscars (46 cm).
• Serpae tetraOscars grow to 46 cm and eat animals they can swallow; serpae tetras grow to 4 cm.
• Siamese algae eaterOscars grow to 46 cm and eat animals they can swallow; Siamese algae eaters grow to 16 cm.
• SwordtailOscars grow to 46 cm and eat animals they can swallow; swordtails grow to 14 cm.
• Tiger barbOscars grow to 46 cm and eat animals they can swallow; tiger barbs grow to 7 cm.
• White cloud mountain minnowOscars grow to 46 cm and eat animals they can swallow; white cloud mountain minnows grow to 4 cm. The only temperature that suits both is 22 °C (72 °F), set by oscars and white cloud mountain minnows. That leaves no margin.
• Yoyo loachOscars grow to 46 cm and eat animals they can swallow; yoyo loaches grow to 16 cm.
• Zebra danioOscars grow to 46 cm and eat animals they can swallow; zebra danios grow to 5 cm.

Sources

Where sources differ, the value shown is computed as the most cautious one.

Behaviour notes are from Seriously Fish, read 2026-10-26.

Check against another species Plan a tank