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Oscars are big, intelligent cichlids that recognise their owners, beg for food and even sulk. Many keepers describe them as the closest thing to a pet dog in an aquarium. They grow fast and get big, though, so they need a large tank and serious filtration.
Oscars at a glance
| Adult size | 30–35cm |
| Minimum tank (one adult) | 300 litres, 120cm+ long |
| Pair | 450 litres+ |
| Temperature | 24–28°C |
| pH | 6.0–7.5 |
| Lifespan | 10–15+ years |
Varieties
Popular types include the red tiger oscar, albino red tiger, lemon oscar and wild-type oscar. See all oscars.
Tank size
Oscars are sold at 4–6cm but can reach 25cm within a year. Buy the tank for the adult fish. Browse our aquariums for larger tanks. Use a heavy, secure lid; oscars can jump.
Filtration
Oscars are messy eaters and produce lots of waste. Aim for a filter turnover of at least 5–10 times the tank volume per hour, ideally with two external filters. Change 25–40% of the water every week and keep nitrate low. Read how to lower ammonia, nitrite and nitrate.
Decor
Oscars rearrange their tank. Use sand or smooth gravel, large rocks that can't topple, and sturdy driftwood. Most plants will be uprooted, so use tough plants attached to wood or skip them. Protect heaters with a guard or use an in-line heater.
Feeding
- Use a quality cichlid pellet or stick such as Tetra Cichlid Sticks XXL as the staple.
- Add frozen foods such as krill and mysis.
- Avoid feeding live feeder fish, which can carry disease, and avoid fatty mammal meat.
- Feed juveniles daily and adults once a day or every other day.
Tankmates
Oscars will eat any fish that fits in their mouth. In a large enough tank, suitable companions include other large South American cichlids, silver dollars, large plecos and robust cichlids of similar size. Many owners keep a single oscar alone.
Common health problems
- Hole in the head: pitting around the head, linked to poor water, high nitrate, activated carbon overuse and poor diet.
- Not eating: often stress after a move or water change. Oscars can sulk for a few days.
- Cloudy eyes and fin rot: almost always water quality. See our fin rot guide.
