Spotted Knifefish Tank Mates

Spotted Knifefish is aggressive, so its tank mates need choosing with care. Here are the 1 freshwater species that pair well with a spotted knifefish — plus the 279 to avoid — with a live checker you can tune to your own tank.

By The Aquarium DB Team • Updated June 7, 2026 • Full Spotted Knifefish care guide →
Best matches

The best tank mates for a spotted knifefish

  • Elephant-nose Knifefish ✅ Compatible
    Hard care · Peaceful · 35 cm · 24–29 °C (75–84 °F)
    Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
With caution

Spotted Knifefish tank mates that can work with care

  • Adolf's Cory ⚠️ With caution
    Medium care · Peaceful · 5.5 cm · 22–26 °C (72–79 °F)
    Spotted 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 caution
    Easy care · Peaceful · 6 cm · 22–28 °C (72–82 °F)
    Spotted 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 caution
    Easy care · Peaceful · 3 cm · 22–26 °C (72–79 °F)
    Spotted 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 caution
    Easy care · Peaceful · 5 cm · 23–28 °C (73–82 °F)
    Spotted 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 caution
    Easy care · Peaceful · 5 cm · 22–27 °C (72–81 °F)
    Spotted 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 caution
    Medium care · Peaceful · 10 cm · 18–24 °C (64–75 °F)
    Spotted Knifefish 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 caution
    Hard care · Peaceful · 60 cm · 22–28 °C (72–82 °F)
    Your 200 L tank is below the ~500 L this pairing really wants — crowding raises aggression.
  • Blood Red Tiger Pleco ⚠️ With caution
    Medium care · Peaceful · 6 cm · 24–29 °C (75–84 °F)
    Spotted 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.

+ 52 more “with caution” pairings — see the interactive checker above.

Avoid

Fish to avoid keeping with a spotted knifefish

  • Mekong Giant Catfish ⛔ Avoid
    Hard care · Semi-aggressive · 300 cm · 20–28 °C (68–82 °F)
    Two assertive fish, one genuinely aggressive: Spotted Knifefish and Mekong Giant Catfish will hold territory and clash.
  • Wels Catfish ⛔ Avoid
    Hard care · Aggressive · 300 cm · 15–25 °C (59–77 °F)
    Two assertive fish, one genuinely aggressive: Spotted Knifefish and Wels Catfish will hold territory and clash.
  • Alligator Gar ⛔ Avoid
    Hard care · Aggressive · 250 cm · 24–28 °C (75–82 °F)
    Two assertive fish, one genuinely aggressive: Spotted Knifefish and Alligator Gar will hold territory and clash.
  • Redtail Catfish ⛔ Avoid
    Hard care · Aggressive · 120 cm · 24–27 °C (75–81 °F)
    Two assertive fish, one genuinely aggressive: Spotted Knifefish and Redtail Catfish will hold territory and clash.
  • Fire Eel ⛔ Avoid
    Medium care · Semi-aggressive · 100 cm · 24–28 °C (75–82 °F)
    Spotted Knifefish and Fire Eel are both territorial and at least one is outright aggressive — expect serious fighting.
  • Clown Knifefish ⛔ Avoid
    Hard care · Aggressive · 90 cm · 24–28 °C (75–82 °F)
    Spotted Knifefish and Clown Knifefish are both territorial and at least one is outright aggressive — expect serious fighting.
  • Spotted Gar ⛔ Avoid
    Hard care · Aggressive · 90 cm · 18–26 °C (64–79 °F)
    Two assertive fish, one genuinely aggressive: Spotted Knifefish and Spotted Gar will hold territory and clash.
  • Wolf Cichlid ⛔ Avoid
    Hard care · Aggressive · 72 cm · 24–30 °C (75–86 °F)
    Spotted Knifefish and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.

+ 271 more to avoid — the checker above flags every one.

Interactive tool

Check any fish against a spotted knifefish

Dial in your exact tank size and filter by result — the checker scores every species in our database against a spotted knifefish, with the reasoning for each verdict.

Tank-mate checker

Will it live with a Spotted Knifefish?

We compare each fish against your spotted knifefish on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.

  • Elephant-nose Knifefish✅ Compatible
    Peaceful · 35 cm · Hard care · 24–29 °C (75–84 °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.
  • Black Doras Catfish⚠️ With caution
    Peaceful · 60 cm · Hard care · 22–28 °C (72–82 °F)
    • Your 200 L tank is below the ~500 L this pairing really wants — crowding raises aggression.
  • Bristlenose Pleco⚠️ With caution
    Peaceful · 12 cm · Easy care · 23–30 °C (73–86 °F)
    • Spotted Knifefish 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 caution
    Peaceful · 30 cm · Medium care · 25–30 °C (77–86 °F)
    • Your 200 L tank is below the ~400 L this pairing really wants — crowding raises aggression.
  • Common Pleco⚠️ With caution
    Peaceful · 45 cm · Medium care · 22–28 °C (72–82 °F)
    • Your 200 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
  • Discus⚠️ With caution
    Peaceful · 20 cm · Hard care · 28–31 °C (82–88 °F)
    • Spotted Knifefish clearly outsizes Discus and is aggressive; risky unless the tank is big and well-planted.
    • Discus is small enough to tempt Spotted Knifefish; only risk it in a densely planted setup with hiding spots.
    • Keep Discus in a shoal of 6+ or it gets stressed and nippy.
  • Giant Glass Catfish⚠️ With caution
    Peaceful · 15 cm · Medium care · 22–27 °C (72–81 °F)
    • Spotted Knifefish is aggressive and may chase or nip the smaller Giant Glass Catfish — plant heavily and break up sight lines.
    • Spotted Knifefish may bully the smaller Giant Glass Catfish, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
  • Goldfish⚠️ With caution
    Peaceful · 30 cm · Medium care · 18–22 °C (64–72 °F)
    • Spotted Knifefish is aggressive and may chase or nip the smaller Goldfish — plant heavily and break up sight lines.
  • Koi⚠️ With caution
    Peaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
    • Spotted Knifefish is small enough to tempt Koi; only risk it in a densely planted setup with hiding spots.
    • Your 200 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
  • Marbled Hoplo⚠️ With caution
    Peaceful · 14 cm · Easy care · 22–28 °C (72–82 °F)
    • Spotted 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 caution
    Peaceful · 12 cm · Medium care · 26–30 °C (79–86 °F)
    • Spotted Knifefish may bully the smaller Medusa Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
  • Rubber Lip Pleco⚠️ With caution
    Peaceful · 12 cm · Easy care · 20–26 °C (68–79 °F)
    • Spotted Knifefish 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 caution
    Peaceful · 50 cm · Medium care · 22–28 °C (72–82 °F)
    • Your 200 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
  • Snowball Pleco⚠️ With caution
    Peaceful · 16 cm · Medium care · 24–30 °C (75–86 °F)
    • Spotted Knifefish may bully the smaller Snowball Pleco, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
  • Spotted Talking Catfish⚠️ With caution
    Peaceful · 15 cm · Easy care · 22–26 °C (72–79 °F)
    • Spotted Knifefish may bully the smaller Spotted Talking Catfish, though its armour makes it a hard meal — give it caves and driftwood to retreat into.
  • Weather Loach⚠️ With caution
    Peaceful · 25 cm · Easy care · 5–24 °C (41–75 °F)
    • Weather Loach is small enough to tempt Spotted Knifefish; only risk it in a densely planted setup with hiding spots.
  • Yellow-spotted Pleco⚠️ With caution
    Peaceful · 35 cm · Medium care · 24–27 °C (75–81 °F)
    • Your 200 L tank is below the ~280 L this pairing really wants — crowding raises aggression.
  • Alligator Gar⛔ Not recommended
    Aggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
    • Two assertive fish, one genuinely aggressive: Spotted Knifefish and Alligator Gar will hold territory and clash.
    • Alligator Gar (250 cm) is big enough to swallow the 45 cm Spotted Knifefish whole.
    • Your 200 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
  • Clown Knifefish⛔ Not recommended
    Aggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
    • Spotted Knifefish and Clown Knifefish are both territorial and at least one is outright aggressive — expect serious fighting.
    • Clown Knifefish may hunt Spotted Knifefish, fry or shrimplets — safest in a heavily planted tank.
    • Your 200 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
  • Fire Eel⛔ Not recommended
    Semi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
    • Spotted Knifefish and Fire Eel are both territorial and at least one is outright aggressive — expect serious fighting.
    • Fire Eel may hunt Spotted Knifefish, fry or shrimplets — safest in a heavily planted tank.
    • Your 200 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
  • Mekong Giant Catfish⛔ Not recommended
    Semi-aggressive · 300 cm · Hard care · 20–28 °C (68–82 °F)
    • Two assertive fish, one genuinely aggressive: Spotted Knifefish and Mekong Giant Catfish will hold territory and clash.
    • Your 200 L tank is below the ~100000 L this pairing really wants — crowding raises aggression.
  • Redtail Catfish⛔ Not recommended
    Aggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
    • Two assertive fish, one genuinely aggressive: Spotted Knifefish and Redtail Catfish will hold territory and clash.
    • Size gap is too large (120 vs 45 cm): Redtail Catfish will treat Spotted Knifefish as food.
    • Your 200 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
  • Spotted Gar⛔ Not recommended
    Aggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
    • Two assertive fish, one genuinely aggressive: Spotted Knifefish and Spotted Gar will hold territory and clash.
    • Watch for Spotted Gar picking off any spotted knifefish small enough to fit in its mouth.
    • Your 200 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
  • Wels Catfish⛔ Not recommended
    Aggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
    • Two assertive fish, one genuinely aggressive: Spotted Knifefish and Wels Catfish will hold territory and clash.
    • Size gap is too large (300 vs 45 cm): Wels Catfish will treat Spotted Knifefish as food.
    • Your 200 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
  • Wolf Cichlid⛔ Not recommended
    Aggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
    • Spotted Knifefish and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.
    • Watch for Wolf Cichlid picking off any spotted knifefish small enough to fit in its mouth.
    • Your 200 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 spotted knifefish community tank

Give the group a stable, planted 200 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

How to choose the right tank mates for a spotted knifefish

Spotted 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.

Spotted Knifefish grows to about 45 cm, so avoid tank mates small enough to be seen as food — as a rule of thumb, skip anything under roughly 23 cm. Match its water, too: aim for 22–28 °C (72–82 °F), pH 6.5–7.5 and 2–12 dGH. Fish needing very different conditions — coldwater species, or hard-water lovers against a soft-water fish — rarely thrive side by side.

Spotted 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.

FAQ

Frequently asked questions

Can a spotted knifefish live with other fish?

Yes — with the right companions. Our checker finds 1 compatible freshwater species for spotted 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 spotted knifefish?

Easy, peaceful, similarly-sized species top the list — for example Elephant-nose Knifefish. Use the checker above to match against your own tank size.

What fish should you avoid keeping with a spotted 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 spotted knifefish tank mates need?

Start from Spotted Knifefish's own minimum and scale up with every addition. The checker above defaults to a 200 L community tank and flags pairings that need more room — drag the slider to match your setup.

← Back to the full Spotted Knifefish care guide