Overview
The Oscar (Astronotus ocellatus) is a freshwater fish belonging to the family Cichlidae. It thrives at temperatures of 23–27 °C with a pH of 6.0–7.5, and requires a minimum tank volume of 380 litres. Known for its aggressive, territorial; predatory toward smaller fish, it is considered a intermediate-level species. Recognises its owner and will beg for food; rearranges décor and uproots plants readily. Water changes of 25–30 % weekly, stable parameters, and appropriate tank mates are key to long-term success with this species.
Scientific Classification
| Rank | Classification |
|---|---|
| Family | Cichlidae |
| Genus | Astronotus |
| Species | Astronotus ocellatus |
| Water type | freshwater |
| Native range | Amazonas, Orinoco|North America|Neotropical|Putumayo|Cuenca Orinoco y Amazonas |
Natural Habitat
Astronotus ocellatus originates from Amazonas, Orinoco|North America|Neotropical|Putumayo|Cuenca Orinoco y Amazonas. It inhabits freshwater environments and is adapted to the water conditions found in its native range.
Appearance
Adults reach 30–35 cm in length. The body is freshwater and the species displays characteristic coloration suited to its environment.
Behavior
This species is described as a aggressive, territorial; predatory toward smaller fish. It does not school and can be kept individually or in small numbers. Activity level is moderate. Recognises its owner and will beg for food; rearranges décor and uproots plants readily.
| Trait | Value |
|---|---|
| Temperament | aggressive, territorial; predatory toward smaller fish |
| Schooling | No |
| Activity level | moderate |
Water Requirements
| Parameter | Ideal Range | Notes |
|---|---|---|
| Temperature | 23–27°C (73–81°F) | Use a reliable adjustable heater |
| pH | 6–7.5 | Avoid sudden swings |
| Hardness (GH) | 5–20 dGH dGH | Soft to moderately hard |
| Ammonia | 0 ppm | Any detectable ammonia signals a problem |
| Nitrite | 0 ppm | Toxic even at low levels |
| Nitrate | <40 ppm | Manage through regular partial water changes |
| Min. tank | 380L (100 gal) | Larger tanks are easier to keep stable |
Interesting Facts
- Oscars are among the most intelligent freshwater fish and can learn simple tricks.
- The 'eye spot' (ocellus) near the tail base is thought to confuse predators into attacking the wrong end.
- A single Oscar can produce waste equivalent to a much larger fish; robust filtration is essential.
📋 Full Care Guide
Ready to set up a tank for your Oscar? The complete care guide covers tank setup, feeding schedule, common diseases, tank mates, and breeding.
Read Oscar Care Guide →Related Species
Related Species & Guides
This species profile was reviewed for biological accuracy and practical aquarium care guidance. For suspected illness or disease, test your water parameters first and consult an aquatic veterinarian if symptoms persist.