Smaragd Betta Tank Mates

Smaragd Betta is aggressive, so its tank mates need choosing with care. Here are the 51 freshwater species that pair well with a smaragd betta — plus the 175 to avoid — with a live checker you can tune to your own tank.

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

The best tank mates for a smaragd betta

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

Smaragd Betta tank mates that can work with care

  • Amano Shrimp ⚠️ With caution
    Easy care · Peaceful · 5 cm · 18–28 °C (64–82 °F)
    Adult Amano Shrimp might survive with Smaragd Betta, but expect the young to be eaten — plant heavily.
  • Amapá Tetra ⚠️ With caution
    Medium care · Peaceful · 4 cm · 24–27 °C (75–81 °F)
    Smaragd Betta is aggressive and may chase or nip the smaller Amapá Tetra — plant heavily and break up sight lines.
  • 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.
  • Bearded Corydoras ⚠️ With caution
    Medium care · Peaceful · 10 cm · 18–24 °C (64–75 °F)
    Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
  • Black Phantom Tetra ⚠️ With caution
    Easy care · Peaceful · 4.5 cm · 22–28 °C (72–82 °F)
    Smaragd Betta and Black Phantom Tetra are close in size, but the aggressive one tends to dominate — add black phantom tetra in a group to spread the pressure.
  • Blackline Rasbora ⚠️ With caution
    Easy care · Peaceful · 6 cm · 22–28 °C (72–82 °F)
    Smaragd Betta and Blackline Rasbora are close in size, but the aggressive one tends to dominate — add blackline rasbora in a group to spread the pressure.
  • Blackwing Hatchetfish ⚠️ With caution
    Medium care · Peaceful · 3.5 cm · 23–28 °C (73–82 °F)
    Expect Smaragd Betta to harass Blackwing Hatchetfish at times; give dense cover and watch them at feeding.
  • Bloodfin Tetra ⚠️ With caution
    Easy care · Peaceful · 5.5 cm · 18–28 °C (64–82 °F)
    Smaragd Betta is aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.

+ 106 more “with caution” pairings — see the interactive checker above.

Avoid

Fish to avoid keeping with a smaragd betta

  • Mekong Giant Catfish ⛔ Avoid
    Hard care · Semi-aggressive · 300 cm · 20–28 °C (68–82 °F)
    Smaragd Betta and Mekong Giant Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
  • Wels Catfish ⛔ Avoid
    Hard care · Aggressive · 300 cm · 15–25 °C (59–77 °F)
    Smaragd Betta and Wels Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
  • Alligator Gar ⛔ Avoid
    Hard care · Aggressive · 250 cm · 24–28 °C (75–82 °F)
    Smaragd Betta and Alligator Gar are both territorial and at least one is outright aggressive — expect serious fighting.
  • Redtail Catfish ⛔ Avoid
    Hard care · Aggressive · 120 cm · 24–27 °C (75–81 °F)
    Smaragd Betta and Redtail Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
  • Fire Eel ⛔ Avoid
    Medium care · Semi-aggressive · 100 cm · 24–28 °C (75–82 °F)
    Two assertive fish, one genuinely aggressive: Smaragd Betta and Fire Eel will hold territory and clash.
  • Clown Knifefish ⛔ Avoid
    Hard care · Aggressive · 90 cm · 24–28 °C (75–82 °F)
    Two assertive fish, one genuinely aggressive: Smaragd Betta and Clown Knifefish will hold territory and clash.
  • Koi ⛔ Avoid
    Medium care · Peaceful · 90 cm · 4–28 °C (39–82 °F)
    Smaragd Betta is bite-sized to a 90 cm koi — it will be eaten.
  • Spotted Gar ⛔ Avoid
    Hard care · Aggressive · 90 cm · 18–26 °C (64–79 °F)
    Smaragd Betta and Spotted Gar are both territorial and at least one is outright aggressive — expect serious fighting.

+ 167 more to avoid — the checker above flags every one.

Interactive tool

Check any fish against a smaragd betta

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

Tank-mate checker

Will it live with a Smaragd Betta?

We compare each fish against your smaragd betta 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)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • 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)
    • Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Agassiz's Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Axelrod's Cory✅ Compatible
    Peaceful · 5 cm · Easy care · 23–28 °C (73–82 °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.
    • Keep Axelrod's Cory in a shoal of 6+ or it gets stressed and nippy.
  • Bandit Corydoras✅ Compatible
    Peaceful · 5 cm · Easy care · 22–27 °C (72–81 °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.
    • Keep Bandit Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Blood Red Tiger Pleco✅ Compatible
    Peaceful · 6 cm · Medium care · 24–29 °C (75–84 °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.
  • Butterfly Hillstream Loach✅ Compatible
    Peaceful · 6 cm · Hard care · 18–24 °C (64–75 °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.
  • Celebes Rainbowfish✅ Compatible
    Peaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
    • Compatible on the things that matter: shared water near 23–28 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Celebes Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Corydoras Catfish✅ Compatible
    Peaceful · 6.5 cm · Easy care · 22–26 °C (72–79 °F)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Corydoras Catfish in a shoal of 6+ or it gets stressed and nippy.
  • Costa's Tetra✅ Compatible
    Peaceful · 7 cm · Easy care · 22–28 °C (72–82 °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.
    • Keep Costa's Tetra 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)
    • 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 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)
    • Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
    • 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)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep False Julii Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • German Blue Ram✅ Compatible
    Peaceful · 6 cm · Hard care · 27–30 °C (81–86 °F)
    • Compatible on the things that matter: shared water near 27–28 °C, workable temperaments, and no predator-and-prey size gap.
  • Hillstream Loach✅ Compatible
    Peaceful · 6 cm · Hard care · 20–24 °C (68–75 °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.
  • Narcissus II Cory✅ Compatible
    Peaceful · 5.5 cm · Medium care · 22–26 °C (72–79 °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.
    • 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)
    • Compatible on the things that matter: shared water near 23–23 °C, workable temperaments, and no predator-and-prey size gap.
  • Peacock Gudgeon✅ Compatible
    Peaceful · 7 cm · Medium care · 22–28 °C (72–82 °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.
  • Peppered Corydoras✅ Compatible
    Peaceful · 7 cm · Easy care · 18–26 °C (64–79 °F)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Peppered Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Rio Negro Checkerboard Cichlid✅ Compatible
    Peaceful · 7 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.
  • Rust Corydoras✅ Compatible
    Peaceful · 5.5 cm · Easy care · 23–27 °C (73–81 °F)
    • Compatible on the things that matter: shared water near 23–27 °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 23–28 °C, workable temperaments, and no predator-and-prey size gap.
    • Keep Slate Corydoras 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)
    • Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
    • 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)
    • Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 23–27 °C — no size, zone or temperament conflicts.
    • 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)
    • Aggressive + Peaceful, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
    • Keep Sterbai Corydoras in a shoal of 6+ or it gets stressed and nippy.
  • Amano Shrimp⚠️ With caution
    Peaceful · 5 cm · Easy care · 18–28 °C (64–82 °F)
    • Adult Amano Shrimp might survive with Smaragd Betta, but expect the young to be eaten — plant heavily.
  • Blackline Rasbora⚠️ With caution
    Peaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
    • Smaragd Betta and Blackline Rasbora are close in size, but the aggressive one tends to dominate — add blackline rasbora in a group to spread the pressure.
    • Keep Blackline Rasbora in a shoal of 6+ or it gets stressed and nippy.
  • Bloodfin Tetra⚠️ With caution
    Peaceful · 5.5 cm · Easy care · 18–28 °C (64–82 °F)
    • Smaragd Betta is aggressive and may chase or nip the smaller Bloodfin Tetra — plant heavily and break up sight lines.
    • Keep Bloodfin 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)
    • 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.
  • Checkered Barb⚠️ With caution
    Peaceful · 5 cm · Easy care · 20–25 °C (68–77 °F)
    • Expect Smaragd Betta to harass Checkered Barb at times; give dense cover and watch them at feeding.
    • Keep Checkered Barb 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)
    • Smaragd Betta 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.
  • Diamond Tetra⚠️ With caution
    Peaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
    • Smaragd Betta and Diamond Tetra are close in size, but the aggressive one tends to dominate — add diamond tetra in a group to spread the pressure.
    • Keep Diamond Tetra in a shoal of 6+ or it gets stressed and nippy.
  • Dwarf Chain Loach⚠️ With caution
    Peaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
    • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
    • Keep Dwarf Chain Loach in a shoal of 6+ or it gets stressed and nippy.
  • Glass Bloodfin Tetra⚠️ With caution
    Peaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
    • Smaragd Betta is aggressive and may chase or nip the smaller Glass Bloodfin Tetra — plant heavily and break up sight lines.
    • Keep Glass Bloodfin Tetra in a shoal of 6+ or it gets stressed and nippy.
  • Guppy⚠️ With caution
    Peaceful · 6 cm · Easy care · 22–28 °C (72–82 °F)
    • Smaragd Betta is aggressive and may chase or nip the smaller Guppy — plant heavily and break up sight lines.
  • Melon Barb⚠️ With caution
    Peaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
    • 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.
  • Neon Dwarf Rainbowfish⚠️ With caution
    Peaceful · 6 cm · Easy care · 23–27 °C (73–81 °F)
    • Smaragd Betta is aggressive and may chase or nip the smaller Neon Dwarf Rainbowfish — plant heavily and break up sight lines.
    • Keep Neon Dwarf Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Pearl Danio⚠️ With caution
    Peaceful · 6 cm · Easy care · 20–25 °C (68–77 °F)
    • Smaragd Betta is aggressive and may chase or nip the smaller Pearl Danio — plant heavily and break up sight lines.
    • Keep Pearl Danio in a shoal of 6+ or it gets stressed and nippy.
  • Platy⚠️ With caution
    Peaceful · 6 cm · Easy care · 21–28 °C (70–82 °F)
    • Expect Smaragd Betta to harass Platy at times; give dense cover and watch them at feeding.
  • Rounded Filament Barb⚠️ With caution
    Peaceful · 7 cm · Medium care · 22–27 °C (72–81 °F)
    • 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.
  • Samurai Gourami⚠️ With caution
    Peaceful · 6 cm · Hard care · 24–28 °C (75–82 °F)
    • Expect Smaragd Betta to harass Samurai Gourami at times; give dense cover and watch them at feeding.
    • Smaragd Betta and Samurai Gourami are both labyrinth fish and often treat each other as rivals — give a large, broken-up tank and be ready to separate them.
  • Alligator Gar⛔ Not recommended
    Aggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
    • Smaragd Betta and Alligator Gar are both territorial and at least one is outright aggressive — expect serious fighting.
    • Size gap is too large (250 vs 6 cm): Alligator Gar will treat Smaragd Betta as food.
    • 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)
    • Two assertive fish, one genuinely aggressive: Smaragd Betta and Clown Knifefish will hold territory and clash.
    • Size gap is too large (90 vs 6 cm): Clown Knifefish will treat Smaragd Betta as food.
    • 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)
    • Two assertive fish, one genuinely aggressive: Smaragd Betta and Fire Eel will hold territory and clash.
    • Fire Eel (100 cm) is big enough to swallow the 6 cm Smaragd Betta whole.
    • 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)
    • Smaragd Betta is bite-sized to a 90 cm koi — it will be eaten.
    • Your 75 L tank is below the ~3800 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)
    • Smaragd Betta and Mekong Giant Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
    • Your 75 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)
    • Smaragd Betta and Redtail Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
    • Smaragd Betta is bite-sized to a 120 cm predatory redtail catfish — it will be eaten.
    • 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)
    • Smaragd Betta and Spotted Gar are both territorial and at least one is outright aggressive — expect serious fighting.
    • Size gap is too large (90 vs 6 cm): Spotted Gar will treat Smaragd Betta as food.
    • 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)
    • Smaragd Betta and Wels Catfish are both territorial and at least one is outright aggressive — expect serious fighting.
    • Smaragd Betta is bite-sized to a 300 cm predatory wels catfish — it will be eaten.
    • Your 75 L tank is below the ~20000 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 smaragd betta 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 smaragd betta

Smaragd Betta 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 top of the tank, so it pairs naturally with species that use the other levels.

Smaragd Betta grows to about 6 cm, so avoid tank mates small enough to be seen as food — as a rule of thumb, skip anything under roughly 3 cm. Match its water, too: aim for 23–28 °C (73–82 °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.

Smaragd Betta 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 smaragd betta live with other fish?

Yes — with the right companions. Our checker finds 51 compatible freshwater species for smaragd betta. 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 smaragd betta?

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 smaragd betta?

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 smaragd betta tank mates need?

Start from Smaragd Betta'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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