Roundtail Paradise Fish Tank Mates

Roundtail Paradise Fish is semi-aggressive, so its tank mates need choosing with care. Here are the 46 freshwater species that pair well with a roundtail paradise fish — plus the 86 to avoid — with a live checker you can tune to your own tank.

By The Aquarium DB Team • Updated June 8, 2026 • Full Roundtail Paradise Fish care guide →
Best matches

The best tank mates for a roundtail paradise fish

  • Assassin Snail ✅ Compatible
    Easy care · Peaceful · 3 cm · 22–26 °C (72–79 °F)
    Semi-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.
  • Malaysian Trumpet Snail ✅ Compatible
    Easy care · Peaceful · 3 cm · 21–27 °C (70–81 °F)
    Compatible on the things that matter: shared water near 21–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Axelrod's Cory ✅ Compatible
    Easy care · Peaceful · 5 cm · 23–28 °C (73–82 °F)
    Semi-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.
  • Bandit Corydoras ✅ Compatible
    Easy care · Peaceful · 5 cm · 22–27 °C (72–81 °F)
    Semi-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.
  • Japanese Trapdoor Snail ✅ Compatible
    Easy care · Peaceful · 5 cm · 10–28 °C (50–82 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 10–26 °C — no size, zone or temperament conflicts.
  • Julii Corydoras ✅ Compatible
    Easy care · Peaceful · 5 cm · 23–26 °C (73–79 °F)
    Semi-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.
  • Masked Corydoras ✅ Compatible
    Easy care · Peaceful · 5 cm · 22–28 °C (72–82 °F)
    Semi-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.
  • Skunk Corydoras ✅ Compatible
    Easy care · Peaceful · 5 cm · 22–26 °C (72–79 °F)
    Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Rust Corydoras ✅ Compatible
    Easy care · Peaceful · 5.5 cm · 23–27 °C (73–81 °F)
    Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Agassiz's Corydoras ✅ Compatible
    Easy care · Peaceful · 6 cm · 22–28 °C (72–82 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
  • Elegant Cory ✅ Compatible
    Easy care · Peaceful · 6 cm · 22–28 °C (72–82 °F)
    Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
  • False Julii Corydoras ✅ Compatible
    Easy care · Peaceful · 6 cm · 22–26 °C (72–79 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
  • Corydoras Catfish ✅ Compatible
    Easy care · Peaceful · 6.5 cm · 22–26 °C (72–79 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
  • Spotfin Corydoras ✅ Compatible
    Easy care · Peaceful · 6.5 cm · 22–26 °C (72–79 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
  • Peppered Corydoras ✅ Compatible
    Easy care · Peaceful · 7 cm · 18–26 °C (64–79 °F)
    Semi-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 Corydoras ✅ Compatible
    Easy care · Peaceful · 7 cm · 22–27 °C (72–81 °F)
    Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Gold Barb ✅ Compatible
    Easy care · Peaceful · 7.5 cm · 18–26 °C (64–79 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 18–26 °C — no size, zone or temperament conflicts.
  • Black Kuhli Loach ✅ Compatible
    Easy care · Peaceful · 8 cm · 23–28 °C (73–82 °F)
    Semi-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.
  • Brilliant Rasbora ✅ Compatible
    Easy care · Peaceful · 9 cm · 22–28 °C (72–82 °F)
    Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Burmese Loach ✅ Compatible
    Easy care · Peaceful · 9 cm · 22–28 °C (72–82 °F)
    Semi-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.
  • Kuhli Loach ✅ Compatible
    Easy care · Peaceful · 10 cm · 24–30 °C (75–86 °F)
    Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Molly ✅ Compatible
    Easy care · Peaceful · 10 cm · 23–28 °C (73–82 °F)
    Semi-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.
  • Murray River Rainbowfish ✅ Compatible
    Easy care · Peaceful · 11 cm · 15–26 °C (59–79 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 15–26 °C — no size, zone or temperament conflicts.
  • Giant Kuhli Loach ✅ Compatible
    Easy care · Peaceful · 12 cm · 24–30 °C (75–86 °F)
    Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–26 °C — no size, zone or temperament conflicts.
With caution

Roundtail Paradise Fish tank mates that can work with care

  • Afra Cichlid ⚠️ With caution
    Medium care · Semi-aggressive · 10 cm · 24–28 °C (75–82 °F)
    Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
  • African Butterfly Cichlid ⚠️ With caution
    Medium care · Semi-aggressive · 8 cm · 22–28 °C (72–82 °F)
    Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
  • Agassiz's Dwarf Cichlid ⚠️ With caution
    Medium care · Semi-aggressive · 9 cm · 24–30 °C (75–86 °F)
    Roundtail Paradise Fish and Agassiz's Dwarf Cichlid can both be territorial; doable with space and dense planting, but watch for chasing.
  • Amano Shrimp ⚠️ With caution
    Easy care · Peaceful · 5 cm · 18–28 °C (64–82 °F)
    Roundtail Paradise Fish may eat Amano Shrimp or pick off its shrimplets — a densely planted tank with moss gives them a fighting chance.
  • Amapá Tetra ⚠️ With caution
    Medium care · Peaceful · 4 cm · 24–27 °C (75–81 °F)
    Roundtail Paradise Fish clearly outsizes Amapá Tetra and is semi-aggressive; risky unless the tank is big and well-planted.
  • Amazon Puffer ⚠️ With caution
    Medium care · Peaceful · 8 cm · 23–28 °C (73–82 °F)
    Your 75 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
  • Angelfish ⚠️ With caution
    Medium care · Semi-aggressive · 15 cm · 24–30 °C (75–86 °F)
    Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
  • Ash Lipped Apisto ⚠️ With caution
    Hard care · Semi-aggressive · 7 cm · 24–29 °C (75–84 °F)
    Roundtail Paradise Fish and Ash Lipped Apisto can both be territorial; doable with space and dense planting, but watch for chasing.

+ 200 more “with caution” pairings — see the interactive checker above.

Avoid

Fish to avoid keeping with a roundtail paradise fish

  • Wels Catfish ⛔ Avoid
    Hard care · Aggressive · 300 cm · 15–25 °C (59–77 °F)
    Two assertive fish, one genuinely aggressive: Roundtail Paradise Fish 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: Roundtail Paradise Fish 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: Roundtail Paradise Fish and Redtail Catfish will hold territory and clash.
  • Fire Eel ⛔ Avoid
    Medium care · Semi-aggressive · 100 cm · 24–28 °C (75–82 °F)
    Fire Eel (100 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
  • Clown Knifefish ⛔ Avoid
    Hard care · Aggressive · 90 cm · 24–28 °C (75–82 °F)
    Roundtail Paradise Fish and Clown Knifefish are both territorial and at least one is outright aggressive — expect serious fighting.
  • Koi ⛔ Avoid
    Medium care · Peaceful · 90 cm · 4–28 °C (39–82 °F)
    Koi (90 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
  • Spotted Gar ⛔ Avoid
    Hard care · Aggressive · 90 cm · 18–26 °C (64–79 °F)
    Two assertive fish, one genuinely aggressive: Roundtail Paradise Fish and Spotted Gar will hold territory and clash.
  • Wolf Cichlid ⛔ Avoid
    Hard care · Aggressive · 72 cm · 24–30 °C (75–86 °F)
    Roundtail Paradise Fish and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.

+ 78 more to avoid — the checker above flags every one.

Interactive tool

Check any fish against a roundtail paradise fish

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

Tank-mate checker

Will it live with a Roundtail Paradise Fish?

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

  • Adolf's Cory✅ Compatible
    Peaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °F)
    • Semi-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.
    • Keep Adolf's Cory in a shoal of 6+ or it gets stressed and nippy.
  • Agassiz's Corydoras✅ Compatible
    Peaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
    • Keep Agassiz's Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Bamboo Shrimp✅ Compatible
    Peaceful · 8 cm · Medium care · 22–27 °C (72–81 °F)
    • Semi-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.
  • Black Kuhli Loach✅ Compatible
    Peaceful · 8 cm · Easy care · 23–28 °C (73–82 °F)
    • Semi-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.
  • Blood Red Tiger Pleco✅ Compatible
    Peaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
    • Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Bolivian Ram✅ Compatible
    Peaceful · 8 cm · Medium care · 24–28 °C (75–82 °F)
    • Semi-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.
  • Brilliant Rasbora✅ Compatible
    Peaceful · 9 cm · Easy care · 22–28 °C (72–82 °F)
    • Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
  • Burmese Loach✅ Compatible
    Peaceful · 9 cm · Easy care · 22–28 °C (72–82 °F)
    • Semi-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.
  • Butterfly Hillstream Loach✅ Compatible
    Peaceful · 6 cm · Hard care · 18–24 °C (64–75 °F)
    • Semi-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.
  • Corydoras Catfish✅ Compatible
    Peaceful · 6.5 cm · Easy care · 22–26 °C (72–79 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
    • Keep Corydoras Catfish in a shoal of 6+ or it gets stressed and nippy.
  • Duplicareus Corydoras✅ Compatible
    Peaceful · 5.5 cm · Medium care · 23–27 °C (73–81 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
    • Keep Duplicareus Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Elegant Cory✅ Compatible
    Peaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
    • Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Elegant Cory in a shoal of 6+ or it gets stressed and nippy.
  • False Julii Corydoras✅ Compatible
    Peaceful · 6 cm · Easy care · 22–26 °C (72–79 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
    • Keep False Julii Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Gold Barb✅ Compatible
    Peaceful · 7.5 cm · Easy care · 18–26 °C (64–79 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 18–26 °C — no size, zone or temperament conflicts.
    • Keep Gold Barb in a shoal of 6+ or it gets stressed and nippy.
  • Hillstream Loach✅ Compatible
    Peaceful · 6 cm · Hard care · 20–24 °C (68–75 °F)
    • Compatible on the things that matter: shared water near 20–24 °C, workable temperaments, and no predator-and-prey size gap.
  • Narcissus II Cory✅ Compatible
    Peaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °F)
    • Semi-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.
    • Keep Narcissus II Cory in a shoal of 6+ or it gets stressed and nippy.
  • Panda Loach✅ Compatible
    Peaceful · 6 cm · Hard care · 18–23 °C (64–73 °F)
    • Semi-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.
  • Peppered Corydoras✅ Compatible
    Peaceful · 7 cm · Easy care · 18–26 °C (64–79 °F)
    • Semi-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.
    • Keep Peppered Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Rust Corydoras✅ Compatible
    Peaceful · 5.5 cm · Easy care · 23–27 °C (73–81 °F)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Rust Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Slate Corydoras✅ Compatible
    Peaceful · 6 cm · Medium care · 23–28 °C (73–82 °F)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Slate Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Splashing Tetra✅ Compatible
    Peaceful · 8 cm · Medium care · 22–28 °C (72–82 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
    • Both favour the top of the tank — offer enough cover so they aren't always in each other's space.
    • Keep Splashing Tetra in a shoal of 6+ or it gets stressed and nippy.
  • Spotfin Corydoras✅ Compatible
    Peaceful · 6.5 cm · Easy care · 22–26 °C (72–79 °F)
    • Semi-aggressive + Peaceful, but with no direct clash here, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
    • Keep Spotfin Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Spotted Corydoras✅ Compatible
    Peaceful · 7 cm · Easy care · 22–27 °C (72–81 °F)
    • Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Spotted Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Sterbai Corydoras✅ Compatible
    Peaceful · 6.5 cm · Medium care · 24–30 °C (75–86 °F)
    • Semi-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.
    • Keep Sterbai Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Ash Lipped Apisto⚠️ With caution
    Semi-aggressive · 7 cm · Hard care · 24–29 °C (75–84 °F)
    • Roundtail Paradise Fish and Ash Lipped Apisto can both be territorial; doable with space and dense planting, but watch for chasing.
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
  • Banded Dwarf Cichlid⚠️ With caution
    Semi-aggressive · 7 cm · Medium care · 24–30 °C (75–86 °F)
    • Roundtail Paradise Fish and Banded Dwarf Cichlid can both be territorial; doable with space and dense planting, but watch for chasing.
  • Bleeding Heart Tetra⚠️ With caution
    Semi-aggressive · 7 cm · Medium care · 23–28 °C (73–82 °F)
    • Roundtail Paradise Fish and Bleeding Heart Tetra can both be territorial; doable with space and dense planting, but watch for chasing.
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
    • Keep Bleeding Heart Tetra in a shoal of 6+ or it gets stressed and nippy.
  • Bright Diamond Tetra⚠️ With caution
    Peaceful · 7 cm · Hard care · 24–28 °C (75–82 °F)
    • Expect Roundtail Paradise Fish to harass Bright Diamond Tetra at times; give dense cover and watch them at feeding.
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
    • Keep Bright Diamond Tetra in a shoal of 8+ or it gets stressed and nippy.
  • Buenos Aires Tetra⚠️ With caution
    Semi-aggressive · 7 cm · Easy care · 18–26 °C (64–79 °F)
    • Roundtail Paradise Fish and Buenos Aires Tetra can both be territorial; doable with space and dense planting, but watch for chasing.
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
    • Keep Buenos Aires Tetra in a shoal of 6+ or it gets stressed and nippy.
  • Celebes Rainbowfish⚠️ With caution
    Peaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
    • Roundtail Paradise Fish is semi-aggressive and may chase or nip the smaller Celebes Rainbowfish — plant heavily and break up sight lines.
    • Keep Celebes Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Costa's Tetra⚠️ With caution
    Peaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
    • Expect Roundtail Paradise Fish to harass Costa's Tetra at times; give dense cover and watch them at feeding.
    • Keep Costa's Tetra in a shoal of 6+ or it gets stressed and nippy.
  • Croaking Gourami⚠️ With caution
    Peaceful · 7 cm · Easy care · 24–28 °C (75–82 °F)
    • Roundtail Paradise Fish and Croaking Gourami are close in size, but the semi-aggressive one tends to dominate — add croaking gourami in a group to spread the pressure.
    • Roundtail Paradise Fish and Croaking Gourami are both labyrinth fish and often treat each other as rivals — give a large, broken-up tank and be ready to separate them.
  • Hongsloi Dwarf Cichlid⚠️ With caution
    Semi-aggressive · 7 cm · Medium care · 24–29 °C (75–84 °F)
    • Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
  • Melon Barb⚠️ With caution
    Peaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
    • Expect Roundtail Paradise Fish to harass Melon Barb at times; give dense cover and watch them at feeding.
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
    • Keep Melon Barb in a shoal of 8+ or it gets stressed and nippy.
  • Peacock Gudgeon⚠️ With caution
    Peaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
    • Expect Roundtail Paradise Fish to harass Peacock Gudgeon at times; give dense cover and watch them at feeding.
  • Rio Negro Checkerboard Cichlid⚠️ With caution
    Peaceful · 7 cm · Hard care · 24–29 °C (75–84 °F)
    • Water hardness preferences differ (Roundtail Paradise Fish 5–20 vs Rio Negro Checkerboard Cichlid 0–4 dGH).
  • Rounded Filament Barb⚠️ With caution
    Peaceful · 7 cm · Medium care · 22–27 °C (72–81 °F)
    • Roundtail Paradise Fish is semi-aggressive and may chase or nip the smaller Rounded Filament Barb — plant heavily and break up sight lines.
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
    • Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
  • Sumo Loach⚠️ With caution
    Semi-aggressive · 7 cm · Medium care · 22–26 °C (72–79 °F)
    • Roundtail Paradise Fish and Sumo Loach can both be territorial; doable with space and dense planting, but watch for chasing.
  • Tiger Barb⚠️ With caution
    Semi-aggressive · 7 cm · Easy care · 22–28 °C (72–82 °F)
    • Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
    • Your 75 L tank is below the ~95 L this pairing really wants — crowding raises aggression.
    • Keep Tiger Barb in a shoal of 6+ or it gets stressed and nippy.
  • Umbrella Dwarf Cichlid⚠️ With caution
    Semi-aggressive · 7 cm · Medium care · 20–26 °C (68–79 °F)
    • Roundtail Paradise Fish and Umbrella Dwarf Cichlid can both be territorial; doable with space and dense planting, but watch for chasing.
  • Alligator Gar⛔ Not recommended
    Aggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
    • Two assertive fish, one genuinely aggressive: Roundtail Paradise Fish and Alligator Gar will hold territory and clash.
    • Alligator Gar (250 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Your 75 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)
    • Roundtail Paradise Fish and Clown Knifefish are both territorial and at least one is outright aggressive — expect serious fighting.
    • Clown Knifefish (90 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Your 75 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)
    • Fire Eel (100 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Both are a bit pushy (semi-aggressive + semi-aggressive) — workable only in a larger tank with cover and broken sight lines.
    • Your 75 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
  • Koi⛔ Not recommended
    Peaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
    • Koi (90 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Your 75 L tank is below the ~3800 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: Roundtail Paradise Fish and Redtail Catfish will hold territory and clash.
    • Redtail Catfish (120 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Your 75 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: Roundtail Paradise Fish and Spotted Gar will hold territory and clash.
    • Roundtail Paradise Fish is bite-sized to a 90 cm predatory spotted gar — it will be eaten.
    • Your 75 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: Roundtail Paradise Fish and Wels Catfish will hold territory and clash.
    • Wels Catfish (300 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Your 75 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)
    • Roundtail Paradise Fish and Wolf Cichlid are both territorial and at least one is outright aggressive — expect serious fighting.
    • Wolf Cichlid (72 cm) is big enough to swallow the 7 cm Roundtail Paradise Fish whole.
    • Your 75 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 roundtail paradise fish community tank

Give the group a stable, planted 75 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 roundtail paradise fish

Being semi-aggressive, roundtail paradise fish can nip or harass smaller, slower or long-finned fish — give it space, broken sight-lines and similarly robust companions. It mostly occupies the top of the tank, so it pairs naturally with species that use the other levels.

Roundtail Paradise Fish grows to about 7 cm, so avoid tank mates small enough to be seen as food — as a rule of thumb, skip anything under roughly 4 cm. Match its water, too: aim for 10–26 °C (50–79 °F), pH 6.5–8 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.

Roundtail Paradise Fish 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 roundtail paradise fish live with other fish?

Yes — with the right companions. Our checker finds 46 compatible freshwater species for roundtail paradise fish. 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 roundtail paradise fish?

Easy, peaceful, similarly-sized species top the list — for example Assassin Snail, Malaysian Trumpet Snail, Axelrod's Cory. Use the checker above to match against your own tank size.

What fish should you avoid keeping with a roundtail paradise fish?

Avoid Wels Catfish, Alligator Gar, Redtail Catfish and similar — usually a temperature, size or temperament clash. The full "avoid" list below gives the reason for each.

How big a tank do roundtail paradise fish tank mates need?

Start from Roundtail Paradise Fish's own minimum and scale up with every addition. The checker above defaults to a 75 L community tank and flags pairings that need more room — drag the slider to match your setup.

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