Clown Knifefish Tank Mates
Clown Knifefish is aggressive, so its tank mates need choosing with care. Here are the 3 freshwater species that pair well with a clown knifefish — plus the 284 to avoid — with a live checker you can tune to your own tank.
The best tank mates for a clown knifefish
- Common Pleco ✅ CompatibleMedium care · Peaceful · 45 cm · 22–28 °C (72–82 °F)Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Sailfin Pleco ✅ CompatibleMedium care · Peaceful · 50 cm · 22–28 °C (72–82 °F)Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Black Doras Catfish ✅ CompatibleHard care · Peaceful · 60 cm · 22–28 °C (72–82 °F)Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
Clown Knifefish tank mates that can work with care
- Adolf's Cory ⚠️ With cautionMedium care · Peaceful · 5.5 cm · 22–26 °C (72–79 °F)Clown Knifefish 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)Clown Knifefish 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)Clown Knifefish 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)Clown Knifefish 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)Clown Knifefish may bully the smaller Bandit Corydoras, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Bearded Corydoras ⚠️ With cautionMedium care · Peaceful · 10 cm · 18–24 °C (64–75 °F)Clown Knifefish may bully the smaller Bearded Corydoras, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Blood Red Tiger Pleco ⚠️ With cautionMedium care · Peaceful · 6 cm · 24–29 °C (75–84 °F)Clown Knifefish may bully the smaller Blood Red Tiger Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Blue Turbo Snail ⚠️ With cautionMedium care · Peaceful · 5 cm · 25–30 °C (77–86 °F)Clown Knifefish may bully the smaller Blue Turbo Snail, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
+ 45 more “with caution” pairings — see the interactive checker above.
Fish to avoid keeping with a clown knifefish
- Mekong Giant Catfish ⛔ AvoidHard care · Semi-aggressive · 300 cm · 20–28 °C (68–82 °F)Two assertive fish, one genuinely aggressive: Clown Knifefish and Mekong Giant Catfish will hold territory and clash.
- Wels Catfish ⛔ AvoidHard care · Aggressive · 300 cm · 15–25 °C (59–77 °F)Two assertive fish, one genuinely aggressive: Clown Knifefish and Wels Catfish will hold territory and clash.
- Alligator Gar ⛔ AvoidHard care · Aggressive · 250 cm · 24–28 °C (75–82 °F)Two assertive fish, one genuinely aggressive: Clown Knifefish and Alligator Gar will hold territory and clash.
- Redtail Catfish ⛔ AvoidHard care · Aggressive · 120 cm · 24–27 °C (75–81 °F)Two assertive fish, one genuinely aggressive: Clown Knifefish and Redtail Catfish will hold territory and clash.
- Fire Eel ⛔ AvoidMedium care · Semi-aggressive · 100 cm · 24–28 °C (75–82 °F)Clown Knifefish and Fire Eel are both territorial and at least one is outright aggressive — expect serious fighting.
- Spotted Gar ⛔ AvoidHard care · Aggressive · 90 cm · 18–26 °C (64–79 °F)Two assertive fish, one genuinely aggressive: Clown Knifefish and Spotted Gar will hold territory and clash.
- Wolf Cichlid ⛔ AvoidHard care · Aggressive · 72 cm · 24–30 °C (75–86 °F)Clown Knifefish and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.
- Giant Gourami ⛔ AvoidMedium care · Semi-aggressive · 70 cm · 22–28 °C (72–82 °F)Two assertive fish, one genuinely aggressive: Clown Knifefish and Giant Gourami will hold territory and clash.
+ 276 more to avoid — the checker above flags every one.
Check any fish against a clown knifefish
Dial in your exact tank size and filter by result — the checker scores every species in our database against a clown knifefish, with the reasoning for each verdict.
Tank-mate checker
Will it live with a Clown Knifefish?
We compare each fish against your clown knifefish on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Black Doras Catfish✅ CompatiblePeaceful · 60 cm · Hard care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Common Pleco✅ CompatiblePeaceful · 45 cm · Medium care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Sailfin Pleco✅ CompatiblePeaceful · 50 cm · Medium care · 22–28 °C (72–82 °F)
- Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Bearded Corydoras⚠️ With cautionPeaceful · 10 cm · Medium care · 18–24 °C (64–75 °F)
- Clown Knifefish 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.
- Bristlenose Pleco⚠️ With cautionPeaceful · 12 cm · Easy care · 23–30 °C (73–86 °F)
- Clown Knifefish may bully the smaller Bristlenose Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Clown Pleco⚠️ With cautionPeaceful · 9 cm · Medium care · 24–28 °C (75–82 °F)
- Clown Knifefish may bully the smaller Clown Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Giant Glass Catfish⚠️ With cautionPeaceful · 15 cm · Medium care · 22–27 °C (72–81 °F)
- Expect Clown Knifefish to harass Giant Glass Catfish at times; give dense cover and watch them at feeding.
- Clown Knifefish may bully the smaller Giant Glass Catfish, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Koi⚠️ With cautionPeaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
- Expect Clown Knifefish to harass Koi at times; give dense cover and watch them at feeding.
- Your 750 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Leopard Frog Pleco⚠️ With cautionPeaceful · 9 cm · Medium care · 25–30 °C (77–86 °F)
- Clown Knifefish may bully the smaller Leopard Frog Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Marbled Hoplo⚠️ With cautionPeaceful · 14 cm · Easy care · 22–28 °C (72–82 °F)
- Clown Knifefish 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)
- Clown Knifefish may bully the smaller Medusa Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Porthole Catfish⚠️ With cautionPeaceful · 10 cm · Easy care · 22–28 °C (72–82 °F)
- Clown Knifefish may bully the smaller Porthole Catfish, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Rubber Lip Pleco⚠️ With cautionPeaceful · 12 cm · Easy care · 20–26 °C (68–79 °F)
- Clown Knifefish may bully the smaller Rubber Lip Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Snowball Pleco⚠️ With cautionPeaceful · 16 cm · Medium care · 24–30 °C (75–86 °F)
- Clown Knifefish may bully the smaller Snowball Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Spotted Rubbernose Pleco⚠️ With cautionPeaceful · 12 cm · Medium care · 20–26 °C (68–79 °F)
- Clown Knifefish may bully the smaller Spotted Rubbernose Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Spotted Talking Catfish⚠️ With cautionPeaceful · 15 cm · Easy care · 22–26 °C (72–79 °F)
- Clown Knifefish may bully the smaller Spotted Talking Catfish, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Upside-down Catfish⚠️ With cautionPeaceful · 10 cm · Easy care · 22–26 °C (72–79 °F)
- Clown Knifefish may bully the smaller Upside-down Catfish, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Yellow-spotted Pleco⚠️ With cautionPeaceful · 35 cm · Medium care · 24–27 °C (75–81 °F)
- Clown Knifefish may bully the smaller Yellow-spotted Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
- Zebra Pleco⚠️ With cautionPeaceful · 10 cm · Hard care · 26–30 °C (79–86 °F)
- Clown Knifefish may bully the smaller Zebra 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)
- Two assertive fish, one genuinely aggressive: Clown Knifefish and Alligator Gar will hold territory and clash.
- Size gap is too large (250 vs 90 cm): Alligator Gar will treat Clown Knifefish as food.
- Your 750 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Fire Eel⛔ Not recommendedSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
- Clown Knifefish and Fire Eel are both territorial and at least one is outright aggressive — expect serious fighting.
- Giant Gourami⛔ Not recommendedSemi-aggressive · 70 cm · Medium care · 22–28 °C (72–82 °F)
- Two assertive fish, one genuinely aggressive: Clown Knifefish and Giant Gourami will hold territory and clash.
- Mekong Giant Catfish⛔ Not recommendedSemi-aggressive · 300 cm · Hard care · 20–28 °C (68–82 °F)
- Two assertive fish, one genuinely aggressive: Clown Knifefish and Mekong Giant Catfish will hold territory and clash.
- Your 750 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)
- Two assertive fish, one genuinely aggressive: Clown Knifefish and Redtail Catfish will hold territory and clash.
- Your 750 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)
- Two assertive fish, one genuinely aggressive: Clown Knifefish and Spotted Gar will hold territory and clash.
- Wels Catfish⛔ Not recommendedAggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
- Two assertive fish, one genuinely aggressive: Clown Knifefish and Wels Catfish will hold territory and clash.
- Clown Knifefish is bite-sized to a 300 cm predatory wels catfish — it will be eaten.
- Your 750 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)
- Clown Knifefish and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.
- Your 750 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 a clown knifefish community tank
Give the group a stable, planted 750 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 a clown knifefish
Clown Knifefish 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 bottom of the tank, so it pairs naturally with species that use the other levels.
Clown Knifefish grows to about 90 cm, so avoid tank mates small enough to be seen as food — as a rule of thumb, skip anything under roughly 45 cm. Match its water, too: aim for 24–28 °C (75–82 °F), pH 6–7.5 and 5–15 dGH. Fish needing very different conditions — coldwater species, or hard-water lovers against a soft-water fish — rarely thrive side by side.
Clown Knifefish 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 a clown knifefish live with other fish?
Yes — with the right companions. Our checker finds 3 compatible freshwater species for clown knifefish. 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 a clown knifefish?
Easy, peaceful, similarly-sized species top the list — for example Common Pleco, Sailfin Pleco, Black Doras Catfish. Use the checker above to match against your own tank size.
What fish should you avoid keeping with a clown knifefish?
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 clown knifefish tank mates need?
Start from Clown Knifefish's own minimum and scale up with every addition. The checker above defaults to a 750 L community tank and flags pairings that need more room — drag the slider to match your setup.