Threadfin Rainbowfish Tank Mates

• African Dwarf Frog✅ Compatible
  Peaceful · 4 cm · Medium care · 22–26 °C (72–79 °F)
  • Both are peaceful, and their water overlaps around 24–26 °C — no size, zone or temperament conflicts.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Amapá Tetra✅ Compatible
  Peaceful · 4 cm · Medium care · 24–27 °C (75–81 °F)
  • Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Amapá Tetra in a shoal of 6+ or it gets stressed and nippy.
• Black Phantom Tetra✅ Compatible
  Peaceful · 4.5 cm · Easy care · 22–28 °C (72–82 °F)
  • Both are peaceful, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Black Phantom Tetra in a shoal of 6+ or it gets stressed and nippy.
• Blue Danio✅ Compatible
  Peaceful · 4 cm · Easy care · 21–26 °C (70–79 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Blue Danio in a shoal of 6+ or it gets stressed and nippy.
• Blue Emperor Tetra✅ Compatible
  Peaceful · 4 cm · Medium care · 23–27 °C (73–81 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Blue Emperor Tetra in a shoal of 6+ or it gets stressed and nippy.
• Cardinal Tetra✅ Compatible
  Peaceful · 4 cm · Medium care · 23–27 °C (73–81 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Cardinal Tetra in a shoal of 6+ or it gets stressed and nippy.
• Emperor Tetra✅ Compatible
  Peaceful · 4 cm · Easy care · 23–27 °C (73–81 °F)
  • Both are peaceful, and their water overlaps around 24–27 °C — no size, zone or temperament conflicts.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Emperor Tetra in a shoal of 6+ or it gets stressed and nippy.
• Flame Tetra✅ Compatible
  Peaceful · 4 cm · Easy 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.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Flame Tetra in a shoal of 6+ or it gets stressed and nippy.
• Glowlight Tetra✅ Compatible
  Peaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
  • Both are peaceful, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Glowlight Tetra in a shoal of 6+ or it gets stressed and nippy.
• Gold Tetra✅ Compatible
  Peaceful · 4.5 cm · Easy care · 23–28 °C (73–82 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Gold Tetra in a shoal of 6+ or it gets stressed and nippy.
• Golden Dwarf Barb✅ Compatible
  Peaceful · 4 cm · Easy care · 18–24 °C (64–75 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Golden Dwarf Barb in a shoal of 6+ or it gets stressed and nippy.
• Jelly Bean Tetra✅ Compatible
  Peaceful · 4 cm · Medium care · 20–26 °C (68–79 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Jelly Bean Tetra in a shoal of 10+ or it gets stressed and nippy.
• Marbled Hatchetfish✅ Compatible
  Peaceful · 4 cm · Medium care · 23–28 °C (73–82 °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 top of the tank — offer enough cover so they aren't always in each other's space.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Marbled Hatchetfish in a shoal of 6+ or it gets stressed and nippy.
• Otocinclus✅ Compatible
  Peaceful · 4 cm · Medium care · 21–26 °C (70–79 °F)
  • Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
• Phoenix Tetra✅ Compatible
  Peaceful · 4 cm · Easy care · 23–28 °C (73–82 °F)
  • Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Phoenix Tetra in a shoal of 8+ or it gets stressed and nippy.
• Purple Tetra✅ Compatible
  Peaceful · 4 cm · Medium care · 22–26 °C (72–79 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Purple Tetra in a shoal of 8+ or it gets stressed and nippy.
• Rainbow Emperor Tetra✅ Compatible
  Semi-aggressive · 3.6 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.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Rainbow Emperor Tetra in a shoal of 8+ or it gets stressed and nippy.
• Red Phantom Tetra✅ Compatible
  Peaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Red Phantom Tetra in a shoal of 8+ or it gets stressed and nippy.
• Rosy Tetra✅ Compatible
  Peaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
  • Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Rosy Tetra in a shoal of 6+ or it gets stressed and nippy.
• Rummy Nose Rasbora✅ Compatible
  Peaceful · 4 cm · Medium care · 20–26 °C (68–79 °F)
  • Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Rummy Nose Rasbora in a shoal of 8+ or it gets stressed and nippy.
• Sparkling Gourami✅ Compatible
  Peaceful · 4 cm · Medium care · 24–28 °C (75–82 °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 top of the tank — offer enough cover so they aren't always in each other's space.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Strawberry Betta✅ Compatible
  Peaceful · 4 cm · Medium care · 22–27 °C (72–81 °F)
  • Both are peaceful, and their water overlaps around 24–27 °C — no size, zone or temperament conflicts.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Tiger Otocinclus✅ Compatible
  Peaceful · 4 cm · Medium care · 22–27 °C (72–81 °F)
  • Both are peaceful, and their water overlaps around 24–27 °C — no size, zone or temperament conflicts.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Tiger Otocinclus in a shoal of 6+ or it gets stressed and nippy.
• Yellow Phantom Tetra✅ Compatible
  Peaceful · 4 cm · Easy care · 23–27 °C (73–81 °F)
  • Compatible on the things that matter: shared water near 24–27 °C, workable temperaments, and no predator-and-prey size gap.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Yellow Phantom Tetra in a shoal of 6+ or it gets stressed and nippy.
• Black Darter Tetra⚠️ With caution
  Semi-aggressive · 4 cm · Hard care · 21–28 °C (70–82 °F)
  • Black Darter Tetra is semi-aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Black Ruby Barb⚠️ With caution
  Semi-aggressive · 6 cm · Easy care · 22–26 °C (72–79 °F)
  • Expect Black Ruby Barb to harass Threadfin Rainbowfish at times; give dense cover and watch them at feeding.
  • Your 75 L tank is below the ~100 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
• Black Skirt Tetra⚠️ With caution
  Semi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
  • Black Skirt Tetra is semi-aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Black Skirt Tetra in a shoal of 6+ or it gets stressed and nippy.
• Cherry Shrimp⚠️ With caution
  Peaceful · 3 cm · Easy care · 18–28 °C (64–82 °F)
  • Threadfin Rainbowfish may eat Cherry Shrimp or pick off its shrimplets — a densely planted tank with moss gives them a fighting chance.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Cherry Shrimp in a shoal of 10+ or it gets stressed and nippy.
• Desert Goby⚠️ With caution
  Semi-aggressive · 6 cm · Easy care · 18–28 °C (64–82 °F)
  • Expect Desert Goby to harass Threadfin Rainbowfish at times; give dense cover and watch them at feeding.
  • Keep Threadfin Rainbowfish 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 Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Dwarf Chain Loach in a shoal of 6+ or it gets stressed and nippy.
• Ghost Shrimp⚠️ With caution
  Peaceful · 4 cm · Easy care · 18–28 °C (64–82 °F)
  • Threadfin Rainbowfish may eat Ghost Shrimp or pick off its shrimplets — a densely planted tank with moss gives them a fighting chance.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Ghost Shrimp in a shoal of 6+ or it gets stressed and nippy.
• Humpbacked Tetra⚠️ With caution
  Semi-aggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
  • Expect Humpbacked Tetra to harass Threadfin Rainbowfish 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 Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
• Morse Code Corydoras⚠️ With caution
  Peaceful · 5 cm · Medium care · 23–26 °C (73–79 °F)
  • Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Morse Code Corydoras in a shoal of 6+ or it gets stressed and nippy.
• Serpae Tetra⚠️ With caution
  Semi-aggressive · 4 cm · Easy care · 23–28 °C (73–82 °F)
  • Serpae Tetra is semi-aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Serpae Tetra in a shoal of 6+ or it gets stressed and nippy.
• Silvertip Tetra⚠️ With caution
  Semi-aggressive · 5 cm · Easy care · 22–28 °C (72–82 °F)
  • Silvertip Tetra and Threadfin Rainbowfish are close in size, but the semi-aggressive one tends to dominate — add threadfin rainbowfish in a group to spread the pressure.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Silvertip Tetra in a shoal of 6+ or it gets stressed and nippy.
• Spotfin Betta⚠️ With caution
  Semi-aggressive · 5 cm · Medium care · 23–28 °C (73–82 °F)
  • Expect Spotfin Betta to harass Threadfin Rainbowfish at times; give dense cover and watch them at feeding.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Striped Red-Eye Puffer⚠️ With caution
  Aggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
  • Striped Red-Eye Puffer is aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Tiger Badis⚠️ With caution
  Semi-aggressive · 4 cm · Medium care · 22–24 °C (72–75 °F)
  • Tiger Badis is semi-aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Tiger Shrimp⚠️ With caution
  Peaceful · 3 cm · Hard care · 20–25 °C (68–77 °F)
  • Threadfin Rainbowfish may eat Tiger Shrimp or pick off its shrimplets — a densely planted tank with moss gives them a fighting chance.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
  • Keep Tiger Shrimp in a shoal of 6+ or it gets stressed and nippy.
• Wine Red Betta⚠️ With caution
  Aggressive · 5 cm · Medium care · 24–28 °C (75–82 °F)
  • Wine Red Betta and Threadfin Rainbowfish are close in size, but the aggressive one tends to dominate — add threadfin rainbowfish in a group to spread the pressure.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Alligator Gar⛔ Not recommended
  Aggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
  • Alligator Gar (250 cm) is big enough to swallow the 4 cm Threadfin Rainbowfish whole.
  • Alligator Gar clearly outsizes Threadfin Rainbowfish and is aggressive; risky unless the tank is big and well-planted.
  • Your 75 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Clown Knifefish⛔ Not recommended
  Aggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
  • Size gap is too large (90 vs 4 cm): Clown Knifefish will treat Threadfin Rainbowfish as food.
  • Clown Knifefish clearly outsizes Threadfin Rainbowfish and is aggressive; risky unless the tank is big and well-planted.
  • Your 75 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Fire Eel⛔ Not recommended
  Semi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
  • Threadfin Rainbowfish is bite-sized to a 100 cm predatory fire eel — it will be eaten.
  • Fire Eel is semi-aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Your 75 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Koi⛔ Not recommended
  Peaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
  • Koi (90 cm) is big enough to swallow the 4 cm Threadfin Rainbowfish whole.
  • Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Redtail Catfish⛔ Not recommended
  Aggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
  • Size gap is too large (120 vs 4 cm): Redtail Catfish will treat Threadfin Rainbowfish as food.
  • Redtail Catfish is aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Your 75 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Spotted Gar⛔ Not recommended
  Aggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
  • Size gap is too large (90 vs 4 cm): Spotted Gar will treat Threadfin Rainbowfish as food.
  • Spotted Gar is aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Your 75 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Wels Catfish⛔ Not recommended
  Aggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
  • Threadfin Rainbowfish is bite-sized to a 300 cm predatory wels catfish — it will be eaten.
  • Wels Catfish is aggressive and may chase or nip the smaller Threadfin Rainbowfish — plant heavily and break up sight lines.
  • Your 75 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
• Wolf Cichlid⛔ Not recommended
  Aggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
  • Size gap is too large (72 vs 4 cm): Wolf Cichlid will treat Threadfin Rainbowfish as food.
  • Wolf Cichlid clearly outsizes Threadfin Rainbowfish and is aggressive; risky unless the tank is big and well-planted.
  • Your 75 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
  • Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.

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.