Best for
Aquariums where its role fits: predator.
Fish · Freshwater
Oscar
Astronotus ocellatus
The Oscar is a large, intelligent predatory cichlid. It is not suitable for small communities or fish that fit in its mouth. Adult size, strength and bioload must be planned from the start.
It may recognize routines and show complex behavior, but that does not reduce its needs: large volume, powerful filtration and robust tankmates.
Difficulty
Intermediate
Aggression
9/10
Schooling
Low
Size
35.00 cm
Minimum volume
300 L
Temperature
24.0-28.0 ºC
Zone
Midwater
Lifespan
12 years
Quick profile scan
fish
Territoriality
Critical
Aggression
9/10
Activity
Moderate
Thermal sensitivity
Medium
Bioload
High
Speed
Moderate
Predation risk
Structural
Expert calculator
Check whether this species fits your aquarium
Analyze volume, parameters, behavior and relationships with other species.
Expert read
Quick verdict
A practical summary to quickly decide whether it fits your aquarium.
Avoid
Mixes marked as high risk or not recommended in manual relationships.
Compatible with
Has positive or conditional references with species such as Bristlenose pleco.
Typical risk
Bioload and adult volume should be planned with margin.
Aquarium zone
Where it lives best
Surface
Midwater
primary
Bottom
Quick compatibility
Community signals
Shrimp
Not recommended
Snails
Conditional
Slow fish
Conditional
Aggressive fish
High risk
Small fish
Not recommended
Large fish
Conditional
Delicate plants
Conditional
Buying decision
Before buying Oscar
Review these points before adding it to your aquarium. They are practical notes based on its profile, ecological data, and known relationships.
L
Adult volume
Make sure your aquarium is above 300 L before buying it.
T
Territory and cover
Prepare visual cover and calm areas if it will live with other species.
P
Prey risk
Do not mix it with fish or invertebrates that may fit in its adult mouth.
B
Bioload
Plan filtration, water changes, and total stocking: this species can heavily load the system.
Parameters
Water conditions
pH
6.0 - 7.5
GH
5 - 15
KH
3 - 8
Temperature
24.0 - 28.0 ºC
Growth and behavior
Juvenile to adult
Juvenile
Juveniles may look more tolerant, but they already show exploratory and opportunistic behavior. Plan the community around adult size, not only the young stage.
Shift
The most important adult change is increased spatial and biological pressure, so the aquarium should be planned for the long term.
Adult
As an adult it strongly shapes the community through size, mouth capacity and feeding behavior. It should only be kept with robust, proportionate species and enough space.
Ecological profile
Role and biological pressure
Predator
Territorial Cichlid
Large
High
Moderate
Structural
Profile: predatory species, with high bioload and primary use of the midwater area. It does not rely on a strong school, but it still needs a balanced community without harassment. It should not be mixed with fish or invertebrates small enough to fit in its mouth. Provide hiding places, visual barriers and enough room to prevent constant pressure.
Ecological radar
profile
Territoriality
96%
Aggression
90%
Activity
52%
Thermal sensitivity
52%
Bioload
78%
Common mistakes
What to avoid
Keeping it in tanks below the recommended adult volume.
Mixing it with species small enough to become prey.
Designing the aquarium without shelter or visual barriers.
Relations
Compatible with
✓
Bristlenose pleco
Conditional
Main risk: Adult space
Review conditions
Astronotus ocellatus + Ancistrus cirrhosus: size difference, activity level or space pressure may cause stress, competition or insufficient usable room.
N
Nerite snail
Conditional
Main risk: Predation
Review conditions
Astronotus ocellatus + Neritina natalensis: there is a predation risk due to size difference, mouth capacity or feeding behavior.
Relations
Avoid keeping with
!
Guppy
Not recommended
Main risk: Predation
Not recommended
Astronotus ocellatus + Poecilia Reticulata: there is a predation risk due to size difference, mouth capacity or feeding behavior.
Zebra danio
Not recommended
Main risk: Predation
Not recommended
Astronotus ocellatus + Danio rerio: there is a predation risk due to size difference, mouth capacity or feeding behavior.
C
Cardinal tetra
Not recommended
Main risk: Predation
Not recommended
Astronotus ocellatus + Paracheirodon axelrodi: there is a predation risk due to size difference, mouth capacity or feeding behavior.
C
Cherry shrimp
Not recommended
Main risk: Predation
Not recommended
Astronotus ocellatus + Neocaridina davidi: there is a predation risk due to size difference, mouth capacity or feeding behavior.
D
Discus
Not recommended
Main risk: Water parameters
Not recommended
Astronotus ocellatus + Symphysodon aequifasciatus: territoriality, dominance or competition for calm areas of the aquarium may occur.
Essential care
Use large aquariums, secure lids and heavy decoration. Avoid neons, guppies, shrimp and small fish. Filtration must handle heavy waste and protein-rich meals.
Daily time
20 min
Breeding
Breeding involves a territorial pair and intense defense. It may move decoration and attack intruders. A very large or dedicated tank is required to avoid harm to other fish.
Oviparous
Moderate
Machos algo más esbeltos; hembras más robustas
Alerts and health
- Acuario muy grande
- Filtración potente
- Decoración robusta
Common issues
Hole in the head
Ich
Expert notes
Interesting details
01
Es una especie muy popular en acuariofilia
02
Se aprecia más cuando se mantiene correctamente
Editorial confidence
Last review: June 2026
Content based on parameters, ecological profiles and manual relationships.
Profile data
Ecological profile
Manual relationships
General aquarium observation
Explore atlas
You may also like
Related species to keep comparing habitat, size, and behavior.
