Photo: Lerdsuwa (CC BY-SA 3.0) — via Wikimedia Commons
Brilliant Rasbora (Rasbora einthovenii)
A sleek, shimmering schooling fish from Borneo that brings elegant motion and a metallic blue stripe to the soft-water community tank.
Will it live with a Brilliant Rasbora?
We compare each fish against your brilliant rasbora on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Badis✅ CompatibleSemi-aggressive · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Banded Dwarf Cichlid✅ CompatibleSemi-aggressive · 7 cm · Medium care · 24–30 °C (75–86 °F)
- Peaceful + Semi-aggressive, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Black Kuhli Loach✅ CompatiblePeaceful · 8 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 Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Bolivian Ram✅ CompatiblePeaceful · 8 cm · Medium care · 24–28 °C (75–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Burmese Loach✅ CompatiblePeaceful · 9 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 Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Celebes Rainbowfish✅ CompatiblePeaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Celebes Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Cockatoo Dwarf Cichlid✅ CompatibleSemi-aggressive · 8 cm · Medium care · 24–28 °C (75–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Costa's Tetra✅ CompatiblePeaceful · 7 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Costa's Tetra in a shoal of 6+ or it gets stressed and nippy.
- Croaking Gourami✅ CompatiblePeaceful · 7 cm · Easy care · 24–28 °C (75–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Dwarf Gourami✅ CompatibleSemi-aggressive · 8 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 middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Gold Barb✅ CompatiblePeaceful · 7.5 cm · Easy care · 18–26 °C (64–79 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Gold Barb in a shoal of 6+ or it gets stressed and nippy.
- Goldeneye Dwarf Cichlid✅ CompatibleSemi-aggressive · 8 cm · Easy care · 24–28 °C (75–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Hongsloi Dwarf Cichlid✅ CompatibleSemi-aggressive · 7 cm · Medium care · 24–29 °C (75–84 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Kuhli Loach✅ CompatiblePeaceful · 10 cm · Easy care · 24–30 °C (75–86 °F)
- Both are peaceful, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Leopard Frog Pleco✅ CompatiblePeaceful · 9 cm · Medium care · 25–30 °C (77–86 °F)
- Compatible on the things that matter: shared water near 25–28 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Mahachai Betta✅ CompatibleAggressive · 7 cm · Medium care · 24–30 °C (75–86 °F)
- Peaceful + Aggressive, but with no direct clash here, and their water overlaps around 24–28 °C — no size, zone or temperament conflicts.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Molly✅ CompatiblePeaceful · 10 cm · Easy care · 23–28 °C (73–82 °F)
- Both are peaceful, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Murray River Rainbowfish✅ CompatiblePeaceful · 11 cm · Easy care · 15–26 °C (59–79 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Murray River Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Peacock Gudgeon✅ CompatiblePeaceful · 7 cm · Medium care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Peppered Corydoras✅ CompatiblePeaceful · 7 cm · Easy care · 18–26 °C (64–79 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Peppered Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Rio Negro Checkerboard Cichlid✅ CompatiblePeaceful · 7 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.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Roundtail Paradise Fish✅ CompatibleSemi-aggressive · 7 cm · Easy care · 10–26 °C (50–79 °F)
- Peaceful + Semi-aggressive, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Splashing Tetra✅ CompatiblePeaceful · 8 cm · Medium 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 Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Splashing Tetra in a shoal of 6+ or it gets stressed and nippy.
- Thick-lipped Gourami✅ CompatiblePeaceful · 9 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 22–28 °C — no size, zone or temperament conflicts.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Afra Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 24–28 °C (75–82 °F)
- pH preferences only just meet (Brilliant Rasbora 5.5–7.5 vs Afra Cichlid 7.8–8.6) — target the overlap and acclimate slowly.
- Afra Cichlid and Brilliant Rasbora are close in size, but the semi-aggressive one tends to dominate — add brilliant rasbora in a group to spread the pressure.
- Your 75 L tank is below the ~150 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Afra Cichlid in a shoal of 6+ or it gets stressed and nippy.
- Agassiz's Dwarf Cichlid⚠️ With cautionSemi-aggressive · 9 cm · Medium care · 24–30 °C (75–86 °F)
- Agassiz's Dwarf Cichlid is semi-aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Bandit Cichlid⚠️ With cautionSemi-aggressive · 9 cm · Medium care · 22–26 °C (72–79 °F)
- Expect Bandit Cichlid to harass Brilliant Rasbora at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~150 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Bandit Cichlid in a shoal of 6+ or it gets stressed and nippy.
- Bearded Corydoras⚠️ With cautionPeaceful · 10 cm · Medium care · 18–24 °C (64–75 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Bearded Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Brichardi Cichlid⚠️ With cautionSemi-aggressive · 9 cm · Medium care · 24–28 °C (75–82 °F)
- pH preferences only just meet (Brilliant Rasbora 5.5–7.5 vs Brichardi Cichlid 7.8–9) — target the overlap and acclimate slowly.
- Expect Brichardi Cichlid to harass Brilliant Rasbora at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Clown Pleco⚠️ With cautionPeaceful · 9 cm · Medium care · 24–28 °C (75–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Clown Rasbora⚠️ With cautionPeaceful · 10 cm · Medium care · 23–28 °C (73–82 °F)
- Your 75 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Clown Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Convict Cichlid⚠️ With cautionAggressive · 10 cm · Easy care · 21–28 °C (70–82 °F)
- Convict Cichlid and Brilliant Rasbora are close in size, but the aggressive one tends to dominate — add brilliant rasbora in a group to spread the pressure.
- Your 75 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Daffodil Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 23–27 °C (73–81 °F)
- Different pH ranges (5.5–7.5 vs 7.8–9); doable if you sit in the shared band, but not ideal long-term.
- Daffodil Cichlid is semi-aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Demasoni Cichlid⚠️ With cautionAggressive · 9 cm · Hard care · 23–27 °C (73–81 °F)
- pH preferences only just meet (Brilliant Rasbora 5.5–7.5 vs Demasoni Cichlid 7.8–8.6) — target the overlap and acclimate slowly.
- Demasoni Cichlid and Brilliant Rasbora are close in size, but the aggressive one tends to dominate — add brilliant rasbora in a group to spread the pressure.
- Your 75 L tank is below the ~200 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Demasoni Cichlid in a shoal of 12+ or it gets stressed and nippy.
- Electric Yellow Cichlid⚠️ With cautionSemi-aggressive · 10 cm · Medium care · 23–26 °C (73–79 °F)
- pH preferences only just meet (Brilliant Rasbora 5.5–7.5 vs Electric Yellow Cichlid 7.8–8.9) — target the overlap and acclimate slowly.
- Electric Yellow Cichlid is semi-aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~200 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Giant Danio⚠️ With cautionPeaceful · 10 cm · Easy care · 20–27 °C (68–81 °F)
- Your 75 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Giant Danio in a shoal of 6+ or it gets stressed and nippy.
- Lifalili Jewel Cichlid⚠️ With cautionAggressive · 9 cm · Medium care · 22–28 °C (72–82 °F)
- Lifalili Jewel Cichlid and Brilliant Rasbora are close in size, but the aggressive one tends to dominate — add brilliant rasbora in a group to spread the pressure.
- Your 75 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Mexican Tetra⚠️ With cautionSemi-aggressive · 9 cm · Easy care · 18–25 °C (64–77 °F)
- Expect Mexican Tetra to harass Brilliant Rasbora at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~110 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Mexican Tetra in a shoal of 6+ or it gets stressed and nippy.
- Silver Tetra⚠️ With cautionPeaceful · 9 cm · Easy care · 24–28 °C (75–82 °F)
- Your 75 L tank is below the ~115 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Silver Tetra in a shoal of 6+ or it gets stressed and nippy.
- Zebra Loach⚠️ With cautionPeaceful · 9 cm · Medium care · 23–26 °C (73–79 °F)
- Your 75 L tank is below the ~115 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Alligator Gar⛔ Not recommendedAggressive · 250 cm · Hard care · 24–28 °C (75–82 °F)
- Alligator Gar (250 cm) is big enough to swallow the 9 cm Brilliant Rasbora whole.
- Alligator Gar is aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~3785 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Clown Knifefish⛔ Not recommendedAggressive · 90 cm · Hard care · 24–28 °C (75–82 °F)
- Brilliant Rasbora is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Clown Knifefish is aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~750 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Fire Eel⛔ Not recommendedSemi-aggressive · 100 cm · Medium care · 24–28 °C (75–82 °F)
- Fire Eel (100 cm) is big enough to swallow the 9 cm Brilliant Rasbora whole.
- Fire Eel is semi-aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~380 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Koi⛔ Not recommendedPeaceful · 90 cm · Medium care · 4–28 °C (39–82 °F)
- Brilliant Rasbora 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.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Redtail Catfish⛔ Not recommendedAggressive · 120 cm · Hard care · 24–27 °C (75–81 °F)
- Redtail Catfish (120 cm) is big enough to swallow the 9 cm Brilliant Rasbora whole.
- Redtail Catfish is aggressive and may chase or nip the smaller Brilliant Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~5700 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Spotted Gar⛔ Not recommendedAggressive · 90 cm · Hard care · 18–26 °C (64–79 °F)
- Brilliant Rasbora is bite-sized to a 90 cm predatory spotted gar — it will be eaten.
- Spotted Gar clearly outsizes Brilliant Rasbora and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~600 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Wels Catfish⛔ Not recommendedAggressive · 300 cm · Hard care · 15–25 °C (59–77 °F)
- Wels Catfish (300 cm) is big enough to swallow the 9 cm Brilliant Rasbora whole.
- Wels Catfish clearly outsizes Brilliant Rasbora and is aggressive; risky unless the tank is big and well-planted.
- Your 75 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Wolf Cichlid⛔ Not recommendedAggressive · 72 cm · Hard care · 24–30 °C (75–86 °F)
- Wolf Cichlid (72 cm) is big enough to swallow the 9 cm Brilliant Rasbora whole.
- Expect Wolf Cichlid to harass Brilliant Rasbora at times; give dense cover and watch them at feeding.
- Your 75 L tank is below the ~760 L this pairing really wants — crowding raises aggression.
- Keep Brilliant Rasbora 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.
Brilliant Rasbora care specs
- Care level
- Easy
- Breeding
- Medium
- Max size
- 9 cm (3.5 in)
- Min tank size
- 75 L (19.8 gal)
- Temperature
- 22–28 °C (72–82 °F)
- pH
- 5.5–7.5
- Hardness
- 1–12 dGH
- Lifespan
- 3–5 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Danionidae
- Origin
- Southeast Asia — Borneo, Sumatra, the Malay Peninsula
What is a Brilliant Rasbora?
The Brilliant Rasbora (Rasbora einthovenii), also sold as Einthoven’s rasbora or the Blue-line rasbora, is a medium-to-large schooling cyprinid from the soft, tannin-rich blackwater streams and peat swamps of Borneo, Sumatra and the Malay Peninsula. Adults top out at around 9 cm (3.5 in) — substantially bigger than the nano rasboras that dominate the hobby — and carry a clean, silver body bisected by a bold iridescent blue-black lateral stripe that shimmers under good aquarium lighting. The common name is apt: the stripe has a metallic brilliance that few cyprinids can match.
Classified in the family Danionidae, the Brilliant Rasbora is a shoaling species that spends most of its time in the middle water column. Keep six or more together and the group moves as a single, fluid unit — a visual payoff that makes them a compelling centrepiece in any soft-water planted aquarium. Care difficulty is rated easy; the main requirements are appropriate water chemistry and adequate space.
Where do Brilliant Rasboras come from?
Wild Brilliant Rasboras inhabit the lowland rivers, forest streams and peat swamps of Southeast Asia — specifically Borneo, Sumatra and the Malay Peninsula. These environments are characterised by exceptionally soft, acidic water coloured deep amber by dissolved tannins from decaying leaf litter. Current is typically slow to moderate, the substrate is dark sand or mud, and overhanging vegetation provides shade.
Understanding this origin shapes every care decision. The fish is adapted to water that is both soft (1–12 dGH) and acidic (pH 5.5–7.5), with temperatures that can range from 22–28 °C (72–82 °F) through seasonal variation. Hard, alkaline tap water — common in many homes — is the single biggest source of chronic stress for this species in captivity.
What tank size and setup does a Brilliant Rasbora need?
The minimum tank size is 75 litres (approximately 20 gallons), and that figure assumes a lean stocking list. Because Brilliant Rasboras reach 9 cm (3.5 in) and are active mid-water swimmers, a longer tank is far better than a tall one — aim for at least 90 cm (36 in) in length to give the shoal room to move together and display natural behaviour.
A biotope-inspired setup works well and brings out the best colour:
- Substrate: Dark sand or fine gravel, optionally scattered with a thin layer of dried Indian almond leaves or oak leaves.
- Hardscape: Driftwood pieces and twisted roots to break up the space without blocking swimming lanes.
- Plants: Hardy soft-water species — java fern, Cryptocoryne, Vallisneria, floating frogbit — provide cover without demanding high light.
- Lighting: Subdued or diffused light; heavy floating cover helps tone down bright overhead lights.
- Filtration: Gentle flow. A sponge filter or a canister with a spray-bar or lily-pipe outlet keeps the water clean without battering the fish.
A tight-fitting lid is sensible: rasboras can jump when startled.
What water parameters do Brilliant Rasboras need?
- Temperature: 22–28 °C (72–82 °F)
- pH: 5.5–7.5
- Hardness: 1–12 dGH
Stability matters as much as hitting the right numbers. Cycled, well-oxygenated water with consistent parameters will serve this species far better than a perfect pH that swings by half a unit each week. Fishkeepers on hard tap water should consider using RO water blended with tap water, or conditioning the tank with peat filtration and Indian almond leaves, to soften and acidify naturally.
Keep ammonia and nitrite at zero and nitrate below 20–25 ppm with regular water changes — weekly partial changes of around 20–25% are a practical routine.
What do Brilliant Rasboras eat?
Brilliant Rasboras are omnivores that accept a wide variety of foods in captivity. A varied diet keeps them in top condition:
- Staple: Quality micro-pellets or small flake food sized for a fish up to 9 cm.
- Frozen/live supplement: Daphnia, bloodworms, brine shrimp, and mosquito larvae are all accepted and help maintain vigour and breeding condition.
- Occasional: Finely diced blanched vegetables or spirulina-based foods round out the diet.
Feed small amounts once or twice daily. Rasboras are surface-to-mid-column feeders and will readily take food as it sinks through the water column. Remove uneaten food after a few minutes to keep water quality high.
Are Brilliant Rasboras peaceful — and what fish can live with them?
Brilliant Rasboras are fully peaceful and one of the more straightforward species to integrate into a soft-water community. They pose no threat to tank-mates and are not prone to fin-nipping. The key considerations are water chemistry compatibility and size matching — avoid pairing them with very small nano species (under 3 cm) where the size difference could cause unintentional stress, though direct predation is not expected.
Strong soft-water community companions include:
- Cardinal tetras and other soft-water characins
- Dwarf cichlids (Apistogramma species) that share the same water parameters
- Small loaches (kuhli loach, dwarf chain loach)
- Corydoras species, particularly those preferring soft, warm water
- Other rasboras of comparable size
Avoid species requiring hard, alkaline water, or boisterous fish that would disrupt the shoal’s relaxed schooling. The Brilliant Rasbora’s own group dynamic is a spectacle — give them space to display it.
For a full compatibility breakdown, see Brilliant Rasbora tank mates.
How do you tell male and female Brilliant Rasboras apart?
Sexual dimorphism in this species is present but subtle. Females are noticeably deeper-bodied with a fuller, rounder belly, which becomes especially pronounced when they are gravid (carrying eggs). Males are slimmer and more streamlined in profile. Colouration and stripe intensity are similar between the sexes.
The distinction is easiest to see when viewing the fish from the side in good light, or by comparing multiple individuals side by side. Juveniles can be very difficult to sex reliably; wait until the fish are approaching adult size — around 6–7 cm — for clearer results.
How do Brilliant Rasboras breed?
Brilliant Rasboras are egg scatterers. In a mature, well-planted soft-water aquarium, opportunistic spawning can occur without any deliberate intervention, particularly if the group is well-conditioned on live and frozen foods. However, deliberately raising fry requires more preparation:
- Set up a dedicated breeding tank of around 40–60 litres with very soft, slightly acidic water (pH 6.0–6.5, hardness below 5 dGH), gentle filtration and dense fine-leaved plants or a spawning mop.
- Condition a small group of adults — two or three females and two males — with live foods for a week or two.
- The fish scatter adhesive eggs among fine plants. Remove the adults promptly after spawning; rasboras will eat their own eggs.
- Eggs hatch within 24–36 hours at typical temperatures; fry become free-swimming a few days later.
- First foods: infusoria, commercially prepared fry foods, or freshly hatched brine shrimp nauplii.
We rate breeding difficulty as medium — the conditioning and water preparation are achievable, but raising fry successfully requires consistent attention and appropriately sized food.
What diseases affect Brilliant Rasboras?
Brilliant Rasboras are generally hardy when water parameters are maintained correctly. Most disease outbreaks trace directly to water-quality problems or the introduction of pathogens from unquarantined fish.
Common issues to watch for:
- White spot (Ich / Ichthyophthirius multifiliis): Classic white-spot disease; triggered by sudden temperature drops or stress. Prevention: stable temperature, avoid chilling during water changes.
- Velvet (Oodinium): A golden or rust-coloured dusty film on the body, often worse under raking light. Prevention: quarantine all new fish for at least two to four weeks before adding them to the display tank.
- Fin rot: Ragged or receding fin edges caused by opportunistic bacteria; virtually always linked to poor water quality. Prevention: regular water changes, zero ammonia/nitrite, adequate tank size for stocking level.
- Neon tetra disease / Microsporidian infections: Rare but worth noting in densely stocked community tanks; no cure, so prevention through quarantine and avoiding stressed fish is essential.
Health note: Medication dosing and clinical disease diagnosis are beyond the scope of a care profile. If your fish show unusual symptoms, confirm identification against a reputable aquatic-health or veterinary resource before treating. Always follow product instructions and remove carbon from the filter before any medication course.
How long do Brilliant Rasboras live?
In a well-maintained aquarium, Brilliant Rasboras typically live 3–5 years. Quality of water chemistry — especially keeping them in appropriately soft, acidic water throughout their lives — appears to have a meaningful influence on longevity and overall vitality. Fish kept in hard water often show duller colouration and may be more susceptible to disease over time.
Purchasing captive-bred specimens from a reputable supplier rather than wild-caught individuals can mean the fish are already acclimated to typical aquarium water, which may ease the transition and support a longer, healthier life.
Frequently asked questions
How large does the Brilliant Rasbora grow?
Adults reach around 8–9 cm (about 3.5 in), making them one of the larger rasboras. They need a tank of at least 75 litres with plenty of open swimming room in the middle zone.
What water conditions do Brilliant Rasboras prefer?
They come from blackwater and soft-water streams in Borneo and Sumatra, so they do best in soft, slightly acidic water — pH 5.5–7.5, hardness 1–12 dGH. Hard, alkaline tap water can stress them over time.
What you need to keep a brilliant rasbora
The baseline is a heated, filtered 75 L+ tank: a reliable heater to hold 22–28 °C (72–82 °F), a gentle filter that won't batter a brilliant rasbora in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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