Oscar
Astronotus ocellatus
Synonyms Tiger oscar · Red oscar · Albino oscar · Velvet cichlid · Marble cichlid · Oscar fish · Lemon oscar
Oscar (Astronotus ocellatus) is a semi-aggressive freshwater fish that reaches about 35 cm (13.8 in) and swims in open water. It wants 68–82°F (20–28°C) and pH 6–7.5, can be kept singly, and needs a tank of at least 540 L (143 gal).
At a glance
| Type | Fish |
|---|---|
| Adult size | 35 cm (13.8 in) |
| Minimum tank | 540 L (143 gal) |
| Group size | Can be kept singly |
| Temperature | 68–82°F (20–28°C) |
| pH | 6–7.5 |
| Temperament | Semi-aggressive |
| Lifespan | 10–15 years |
| Eats shrimp | Yes |
Before it goes in
- Oscar needs at least 540 L (143 gal). The smallest size in this library that clears that is the 180P.
- It eats small fish and shrimp — anything under about 11.7 cm (4.6 in). In this library that means Cherry Shrimp, Rummy Nose Tetra and Crystal Red Shrimp.
- It holds at 68–82°F (20–28°C). That shares a window with Betta and Cherry Shrimp.
- Do not put it with Amano Shrimp, Betta and Cardinal Tetra.
- It is semi-aggressive — plan the tank around it rather than adding it to a finished community.
- It digs in the substrate. A freshly planted carpet — Dwarf Hairgrass Mini and Downoi — gets lifted before it roots.
- One of them takes up roughly 17% of what a 180P will comfortably hold, so plan the rest of the stock around it.
What tank size does it need?
At least 540 L (143 gal). The smallest size here that clears it is the 180P.
Will it eat shrimp?
Yes. Shrimp are food to it, so pick one or the other.
What water does it want?
68–82°F (20–28°C), pH 6–7.5.
How long does it live?
10–15 years in a tank that suits it. That is how long you are signing up for.
Good tank mates
- Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Goldfish, Bristlenose Pleco, Molly, Ramshorn Snail and Julii Cory.
- Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.
Often compared with
| Oscar | Bala Shark | Tinfoil Barb | |
|---|---|---|---|
| Adult size | 35 cm | 35 cm | 35.5 cm |
| Min tank | 540 L | 864 L | 756 L |
| Group | 1+ | 5+ | 6+ |
| Temperature | 68–82°F (20–28°C) | 68–82°F (20–28°C) | 68–82°F (20–28°C) |
| Eats shrimp | Yes | Yes | Yes |
More livestock
Sources (5) · checked Sep 2026
- Mature tank, Group sizeseriouslyfish.com
- What it eatsaquariumcoop.com
- What it eatsen.aqua-fish.net
- fishkeepingworld.com
- fishlaboratory.com