Oscar Tank Mates
Oscar is aggressive, so its tank mates need choosing with care. Here are the 5 freshwater species that pair well with an oscar — plus the 277 to avoid — with a live checker you can tune to your own tank.
The best tank mates for an oscar
- Spotted Talking Catfish ✅ CompatibleEasy care · Peaceful · 15 cm · 22–26 °C (72–79 °F)Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Weather Loach ✅ CompatibleEasy care · Peaceful · 25 cm · 5–24 °C (41–75 °F)Aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Snowball Pleco ✅ CompatibleMedium care · Peaceful · 16 cm · 24–30 °C (75–86 °F)Aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Yellow-spotted Pleco ✅ CompatibleMedium care · Peaceful · 35 cm · 24–27 °C (75–81 °F)Aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Elephant-nose Knifefish ✅ CompatibleHard care · Peaceful · 35 cm · 24–29 °C (75–84 °F)Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
Oscar tank mates that can work with care
- Adolf's Cory ⚠️ With cautionMedium care · Peaceful · 5.5 cm · 22–26 °C (72–79 °F)Oscar may bully the smaller Adolf's Cory, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Agassiz's Corydoras ⚠️ With cautionEasy care · Peaceful · 6 cm · 22–28 °C (72–82 °F)Oscar may bully the smaller Agassiz's Corydoras, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Assassin Snail ⚠️ With cautionEasy care · Peaceful · 3 cm · 22–26 °C (72–79 °F)Oscar may bully the smaller Assassin Snail, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Axelrod's Cory ⚠️ With cautionEasy care · Peaceful · 5 cm · 23–28 °C (73–82 °F)Oscar may bully the smaller Axelrod's Cory, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Bandit Corydoras ⚠️ With cautionEasy care · Peaceful · 5 cm · 22–27 °C (72–81 °F)Oscar may bully the smaller Bandit Corydoras, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Banjo Catfish ⚠️ With cautionMedium care · Peaceful · 15 cm · 20–26 °C (68–79 °F)Banjo Catfish is small enough to tempt Oscar; only risk it in a densely planted setup with hiding spots.
- Bearded Corydoras ⚠️ With cautionMedium care · Peaceful · 10 cm · 18–24 °C (64–75 °F)Oscar may bully the smaller Bearded Corydoras, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Black Doras Catfish ⚠️ With cautionHard care · Peaceful · 60 cm · 22–28 °C (72–82 °F)Your 280 L tank is below the ~500 L this pairing really wants — crowding raises aggression.
+ 50 more “with caution” pairings — see the interactive checker above.
Fish to avoid keeping with an oscar
- Mekong Giant Catfish ⛔ AvoidHard care · Semi-aggressive · 300 cm · 20–28 °C (68–82 °F)Oscar and Mekong Giant Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Wels Catfish ⛔ AvoidHard care · Aggressive · 300 cm · 15–25 °C (59–77 °F)Oscar and Wels Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Alligator Gar ⛔ AvoidHard care · Aggressive · 250 cm · 24–28 °C (75–82 °F)Oscar and Alligator Gar are both territorial and at least one is outright aggressive — expect serious fighting.
- Redtail Catfish ⛔ AvoidHard care · Aggressive · 120 cm · 24–27 °C (75–81 °F)Oscar and Redtail Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Fire Eel ⛔ AvoidMedium care · Semi-aggressive · 100 cm · 24–28 °C (75–82 °F)Two assertive fish, one genuinely aggressive: Oscar and Fire Eel will hold territory and clash.
- Clown Knifefish ⛔ AvoidHard care · Aggressive · 90 cm · 24–28 °C (75–82 °F)Two assertive fish, one genuinely aggressive: Oscar and Clown Knifefish will hold territory and clash.
- Spotted Gar ⛔ AvoidHard care · Aggressive · 90 cm · 18–26 °C (64–79 °F)Oscar and Spotted Gar are both territorial and at least one is outright aggressive — expect serious fighting.
- Wolf Cichlid ⛔ AvoidHard care · Aggressive · 72 cm · 24–30 °C (75–86 °F)Two assertive fish, one genuinely aggressive: Oscar and Wolf Cichlid will hold territory and clash.
+ 269 more to avoid — the checker above flags every one.
Check any fish against an oscar
Dial in your exact tank size and filter by result — the checker scores every species in our database against an oscar, with the reasoning for each verdict.
Tank-mate checker
Will it live with a Oscar?
We compare each fish against your oscar on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Elephant-nose Knifefish✅ CompatiblePeaceful · 35 cm · Hard care · 24–29 °C (75–84 °F)
- Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Snowball Pleco✅ CompatiblePeaceful · 16 cm · Medium care · 24–30 °C (75–86 °F)
- Aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Spotted Talking Catfish✅ CompatiblePeaceful · 15 cm · Easy care · 22–26 °C (72–79 °F)
- Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Weather Loach✅ CompatiblePeaceful · 25 cm · Easy care · 5–24 °C (41–75 °F)
- Aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Yellow-spotted Pleco✅ CompatiblePeaceful · 35 cm · Medium care · 24–27 °C (75–81 °F)
- Aggressive + Peaceful, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Banjo Catfish⚠️ With cautionPeaceful · 15 cm · Medium care · 20–26 °C (68–79 °F)
- Banjo Catfish is small enough to tempt Oscar; only risk it in a densely planted setup with hiding spots.
- Bearded Corydoras⚠️ With cautionPeaceful · 10 cm · Medium care · 18–24 °C (64–75 °F)
- Oscar may bully the smaller Bearded Corydoras, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Keep Bearded Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Black Doras Catfish⚠️ With cautionPeaceful · 60 cm · Hard care · 22–28 °C (72–82 °F)
- Your 280 L tank is below the ~500 L this pairing really wants — crowding raises aggression.
- Bristlenose Pleco⚠️ With cautionPeaceful · 12 cm · Easy care · 23–30 °C (73–86 °F)
- Oscar may bully the smaller Bristlenose Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Clown Loach⚠️ With cautionPeaceful · 30 cm · Medium care · 25–30 °C (77–86 °F)
- Your 280 L tank is below the ~400 L this pairing really wants — crowding raises aggression.
- Common Pleco⚠️ With cautionPeaceful · 45 cm · Medium care · 22–28 °C (72–82 °F)
- Your 280 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Denison Barb⚠️ With cautionPeaceful · 15 cm · Medium care · 18–25 °C (64–77 °F)
- Oscar is aggressive and may chase or nip the smaller Denison Barb — plant heavily and break up sight lines.
- Oscar may hunt Denison Barb, fry or shrimplets — safest in a heavily planted tank.
- Keep Denison Barb in a shoal of 6+ or it gets stressed and nippy.
- Discus⚠️ With cautionPeaceful · 20 cm · Hard care · 28–31 °C (82–88 °F)
- Oscar clearly outsizes Discus and is aggressive; risky unless the tank is big and well-planted.
- Watch for Oscar picking off any discus small enough to fit in its mouth.
- Keep Discus in a shoal of 6+ or it gets stressed and nippy.
- Giant Glass Catfish⚠️ With cautionPeaceful · 15 cm · Medium care · 22–27 °C (72–81 °F)
- Expect Oscar to harass Giant Glass Catfish at times; give dense cover and watch them at feeding.
- Koi⚠️ With cautionPeaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
- Koi may hunt Oscar, fry or shrimplets — safest in a heavily planted tank.
- Your 280 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Marbled Hoplo⚠️ With cautionPeaceful · 14 cm · Easy care · 22–28 °C (72–82 °F)
- Oscar may bully the smaller Marbled Hoplo, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Medusa Pleco⚠️ With cautionPeaceful · 12 cm · Medium care · 26–30 °C (79–86 °F)
- Oscar may bully the smaller Medusa Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Moonlight Gourami⚠️ With cautionPeaceful · 15 cm · Easy care · 25–30 °C (77–86 °F)
- Oscar is aggressive and may chase or nip the smaller Moonlight Gourami — plant heavily and break up sight lines.
- Moonlight Gourami is small enough to tempt Oscar; only risk it in a densely planted setup with hiding spots.
- Rubber Lip Pleco⚠️ With cautionPeaceful · 12 cm · Easy care · 20–26 °C (68–79 °F)
- Oscar may bully the smaller Rubber Lip Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Sailfin Pleco⚠️ With cautionPeaceful · 50 cm · Medium care · 22–28 °C (72–82 °F)
- Your 280 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Spotted Rubbernose Pleco⚠️ With cautionPeaceful · 12 cm · Medium care · 20–26 °C (68–79 °F)
- Oscar may bully the smaller Spotted Rubbernose Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Alligator Gar⛔ Not recommendedAggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
- Oscar and Alligator Gar are both territorial and at least one is outright aggressive — expect serious fighting.
- Oscar is bite-sized to a 250 cm predatory alligator gar — it will be eaten.
- Your 280 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Clown Knifefish⛔ Not recommendedAggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
- Two assertive fish, one genuinely aggressive: Oscar and Clown Knifefish will hold territory and clash.
- Oscar is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Your 280 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Fire Eel⛔ Not recommendedSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
- Two assertive fish, one genuinely aggressive: Oscar and Fire Eel will hold territory and clash.
- Size gap is too large (100 vs 35 cm): Fire Eel will treat Oscar as food.
- Your 280 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Mekong Giant Catfish⛔ Not recommendedSemi-aggressive · 300 cm · Hard care · 20–28 °C (68–82 °F)
- Oscar and Mekong Giant Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Your 280 L tank is below the ~100000 L this pairing really wants — crowding raises aggression.
- Redtail Catfish⛔ Not recommendedAggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
- Oscar and Redtail Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Size gap is too large (120 vs 35 cm): Redtail Catfish will treat Oscar as food.
- Your 280 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Spotted Gar⛔ Not recommendedAggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
- Oscar and Spotted Gar are both territorial and at least one is outright aggressive — expect serious fighting.
- Size gap is too large (90 vs 35 cm): Spotted Gar will treat Oscar as food.
- Your 280 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Wels Catfish⛔ Not recommendedAggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
- Oscar and Wels Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
- Size gap is too large (300 vs 35 cm): Wels Catfish will treat Oscar as food.
- Your 280 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Wolf Cichlid⛔ Not recommendedAggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
- Two assertive fish, one genuinely aggressive: Oscar and Wolf Cichlid will hold territory and clash.
- Watch for Wolf Cichlid picking off any oscar small enough to fit in its mouth.
- Your 280 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
Compatibility is computed from each species' care data — a strong starting point, not a guarantee. Individual temperament varies, so always introduce new fish slowly and watch them.
Setting up an oscar community tank
Give the group a stable, planted 280 L+ tank with a gentle filter, a reliable heater and plenty of cover — broken sight lines and hiding spots let mid-water and bottom dwellers keep out of each other's way. Cycle it fully and stock gradually.
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How to choose the right tank mates for an oscar
Oscar is aggressive and territorial, so most community fish are unsafe; any tank mate must be large, tough and able to hold its own. It mostly occupies the middle of the tank, so it pairs naturally with species that use the other levels.
Oscar grows to about 35 cm, so avoid tank mates small enough to be seen as food — as a rule of thumb, skip anything under roughly 18 cm. Match its water, too: aim for 23–28 °C (73–82 °F), pH 6–7.5 and 5–20 dGH. Fish needing very different conditions — coldwater species, or hard-water lovers against a soft-water fish — rarely thrive side by side.
Oscar doesn't need its own kind to feel secure; think twice before keeping more than one if it is territorial. Whatever you add, introduce new fish slowly, watch for bullying in the first days, and have a backup plan if temperaments clash.
Frequently asked questions
Can an oscar live with other fish?
Yes — with the right companions. Our checker finds 5 compatible freshwater species for oscar. Pick calm, similarly-sized fish that share its water needs and add them to a mature, well-planted tank.
What is the best tank mate for an oscar?
Easy, peaceful, similarly-sized species top the list — for example Spotted Talking Catfish, Weather Loach, Snowball Pleco. Use the checker above to match against your own tank size.
What fish should you avoid keeping with an oscar?
Avoid Mekong Giant Catfish, Wels Catfish, Alligator Gar and similar — usually a temperature, size or temperament clash. The full "avoid" list below gives the reason for each.
How big a tank do oscar tank mates need?
Start from Oscar's own minimum and scale up with every addition. The checker above defaults to a 280 L community tank and flags pairings that need more room — drag the slider to match your setup.