Oscar
Astronotus ocellatus
Oscar is a all-zone swimmer. Solitary housing is permitted; group housing needs additional context.
Save this fish or add it directly to one of your aquariums.
Need help with Oscar?
Explore compatibility, care or problems using this guide and your aquarium’s conditions.
Quick facts
- Adult size
- 11.8–15.7" (30–40 cm)
- Aquarium size
- 143 US gal (540 L) or larger / ≥ 59.1" (≥ 150 cm) minimum length
- Care level
- Advanced
- Temperament
- Semi-Aggressive
- Swimming zone
- All-zone swimmer
- Temperature
- 75–79°F (24–26°C)
- pH
- 6–7.5
- GH
- 5–20 dGH
- KH
- 1–10 dKH
- Diet
- Omnivore
- Lifespan
- 10–20 years
- Group behavior
- Solitary housing is permitted; group housing needs additional context
Care requirements
Care level: Advanced.
Lifespan: 10–20 years.
Aquarium size and space needs
Minimum aquarium size: 143 US gal (540 L) or larger / ≥ 59.1" (≥ 150 cm) minimum length. Plan the layout and stocking within that limit.
Water parameters
Suitable water: temperature 24–26 °C, pH 6–7.5, GH 5–20 dGH, KH 1–10 dKH.
Temperament and compatibility
Oscar needs careful companion choice because it can be territorial or semi-aggressive.
Swimming zone and behavior
This fish uses multiple areas of the aquarium, so leave enough open swimming space for movement and feeding.
Feeding
As an omnivore, Oscar should receive a varied diet rather than one repeated food type.
Use quality large cichlid pellets with earthworms, prawns, mussels, insects and occasional plant-based foods. Avoid feeder fish.
Before adding this fish
- Plan for an aquarium of 143 US gal (540 L) or larger / ≥ 59.1" (≥ 150 cm) minimum length.
- Choose other fish carefully around this temperament.
- Solitary housing is permitted; group housing needs additional context.
- Offer a varied diet suited to this species’ documented feeding habits.
Natural habitat and origin
Origin: Amazon and Orinoco river basins.
Natural habitat: Quiet canals, floodplain lakes, ponds and slow river margins with sand, mud, submerged wood and seasonal cover.
Breeding notes
Breeding difficulty: Intermediate - Advanced.
The correct genus is Astronotus. A normal home aquarium should be planned for one adult or a genuinely compatible pair.
Important notes
- Large fish with a heavy biological load.
- Small fish and invertebrates may be eaten.
- Requires secure, stable hardscape and a strong cover.
- Long-term care requires a 150 cm aquarium or larger.
Similar fish profiles
Use these profiles to compare fish with similar care level, size, temperature range, or swimming behavior.
FAQ
How large does Oscar get?
Oscar reaches 11.8–15.7" (30–40 cm). It needs specialist housing, long-term space, strong filtration, and carefully chosen companions.
What aquarium size does Oscar need?
Use an aquarium of at least 143 US gal (540 L) or larger / ≥ 59.1" (≥ 150 cm) minimum length.
Is Oscar peaceful?
Oscar needs more careful companion choice because the temperament data points toward boundaries, space, or similar-sized fish.
What temperature is suitable for Oscar?
Keep it between 24 to 26 °C.
Should Oscar be kept alone or in a group?
Oscar: Solitary housing is permitted; group housing needs additional context.
