Photo: Lerdsuwa (CC BY-SA 3.0) — via Wikimedia Commons
Lambchop Rasbora (Trigonostigma espei)
A slender, copper-and-black nano gem that schools like liquid fire — everything a harlequin rasbora is, just smaller and more delicate.
Will it live with a Lambchop Rasbora?
We compare each fish against your lambchop rasbora on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- Assassin Snail✅ CompatiblePeaceful · 3 cm · Easy 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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Blackwing Hatchetfish✅ CompatiblePeaceful · 3.5 cm · Medium care · 23–28 °C (73–82 °F)
- Both are peaceful, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Blackwing Hatchetfish in a shoal of 6+ or it gets stressed and nippy.
- Cherry Shrimp✅ CompatiblePeaceful · 3 cm · Easy care · 18–28 °C (64–82 °F)
- Both are peaceful, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Keep Lambchop Rasbora 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.
- Clown Killifish✅ CompatiblePeaceful · 3.5 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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Clown Killifish in a shoal of 6+ or it gets stressed and nippy.
- Crimson Red Betta✅ CompatiblePeaceful · 3.5 cm · Hard care · 24–29 °C (75–84 °F)
- Compatible on the things that matter: shared water near 24–28 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Crystal Red Shrimp✅ CompatiblePeaceful · 2.5 cm · Hard care · 20–24 °C (68–75 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Crystal Red Shrimp in a shoal of 10+ or it gets stressed and nippy.
- Dawn Tetra✅ CompatiblePeaceful · 2.5 cm · Easy care · 22–28 °C (72–82 °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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Dawn Tetra in a shoal of 8+ or it gets stressed and nippy.
- Dwarf Spotted Rasbora✅ CompatiblePeaceful · 2.5 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Dwarf Spotted Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Endler's Livebearer✅ CompatiblePeaceful · 3 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 23–28 °C — no size, zone or temperament conflicts.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Endler's Livebearer in a shoal of 6+ or it gets stressed and nippy.
- Eyespot Rasbora✅ CompatiblePeaceful · 3.5 cm · Medium care · 20–25 °C (68–77 °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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Eyespot Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Fire Red Licorice Gourami✅ CompatiblePeaceful · 3.5 cm · Hard 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Glowlight Danio✅ CompatiblePeaceful · 3 cm · Easy 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Glowlight Danio in a shoal of 8+ or it gets stressed and nippy.
- Glowlight Rasbora✅ CompatiblePeaceful · 3.5 cm · Easy 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Glowlight Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Gold Ring Danio✅ CompatiblePeaceful · 3 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Gold Ring Danio in a shoal of 8+ or it gets stressed and nippy.
- Green Neon Tetra✅ CompatiblePeaceful · 2.5 cm · Hard care · 24–28 °C (75–82 °F)
- Both are peaceful, and their water overlaps around 24–28 °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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Green Neon Tetra in a shoal of 8+ or it gets stressed and nippy.
- Malaysian Trumpet Snail✅ CompatiblePeaceful · 3 cm · Easy care · 21–27 °C (70–81 °F)
- Both are peaceful, and their water overlaps around 23–27 °C — no size, zone or temperament conflicts.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Neon Blue Rasbora✅ CompatiblePeaceful · 2.5 cm · Medium care · 23–26 °C (73–79 °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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Neon Blue Rasbora in a shoal of 10+ or it gets stressed and nippy.
- Neon Tetra✅ CompatiblePeaceful · 3 cm · Easy care · 20–26 °C (68–79 °F)
- Both are peaceful, and their water overlaps around 23–26 °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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Neon Tetra in a shoal of 6+ or it gets stressed and nippy.
- Northern Glowlight Danio✅ CompatiblePeaceful · 3.5 cm · Medium 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Northern Glowlight Danio in a shoal of 8+ or it gets stressed and nippy.
- Pygmy Corydoras✅ CompatiblePeaceful · 3.2 cm · Easy 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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Pygmy Corydoras in a shoal of 8+ or it gets stressed and nippy.
- Tail-spot Corydoras✅ CompatiblePeaceful · 3 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.
- Both favour the middle of the tank — offer enough cover so they aren't always in each other's space.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Tail-spot Corydoras in a shoal of 8+ or it gets stressed and nippy.
- Tailspotted Oto✅ CompatiblePeaceful · 3.5 cm · Medium care · 22–27 °C (72–81 °F)
- Compatible on the things that matter: shared water near 23–27 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Keep Tailspotted Oto in a shoal of 6+ or it gets stressed and nippy.
- Tiger Shrimp✅ CompatiblePeaceful · 3 cm · Hard care · 20–25 °C (68–77 °F)
- Both are peaceful, and their water overlaps around 23–25 °C — no size, zone or temperament conflicts.
- Keep Lambchop Rasbora 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.
- Trinidad Guppy✅ CompatiblePeaceful · 3 cm · Easy care · 19–24 °C (66–75 °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 Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Black Darter Tetra⚠️ With cautionSemi-aggressive · 4 cm · Hard care · 21–28 °C (70–82 °F)
- Black Darter Tetra and Lambchop Rasbora are close in size, but the semi-aggressive one tends to dominate — add lambchop rasbora in a group to spread the pressure.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Black Ruby Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 22–26 °C (72–79 °F)
- Black Ruby Barb is semi-aggressive and may chase or nip the smaller Lambchop Rasbora — plant heavily and break up sight lines.
- Watch for Black Ruby Barb picking off any lambchop rasbora small enough to fit in its mouth.
- Your 75 L tank is below the ~100 L this pairing really wants — crowding raises aggression.
- Keep Lambchop Rasbora 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 cautionSemi-aggressive · 6 cm · Easy care · 20–26 °C (68–79 °F)
- Black Skirt Tetra clearly outsizes Lambchop Rasbora and is semi-aggressive; risky unless the tank is big and well-planted.
- Lambchop Rasbora is small enough to tempt Black Skirt Tetra; only risk it in a densely planted setup with hiding spots.
- Keep Lambchop Rasbora 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.
- Blue Turbo Snail⚠️ With cautionPeaceful · 5 cm · Medium care · 25–30 °C (77–86 °F)
- Different pH ranges (5.5–7 vs 7.5–8.5); doable if you sit in the shared band, but not ideal long-term.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Desert Goby⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 18–28 °C (64–82 °F)
- Desert Goby clearly outsizes Lambchop Rasbora and is semi-aggressive; risky unless the tank is big and well-planted.
- Desert Goby may hunt Lambchop Rasbora, fry or shrimplets — safest in a heavily planted tank.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Dwarf Chain Loach⚠️ With cautionPeaceful · 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 Lambchop Rasbora 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.
- Eastern Betta⚠️ With cautionSemi-aggressive · 6 cm · Medium care · 24–28 °C (75–82 °F)
- Expect Eastern Betta to harass Lambchop Rasbora at times; give dense cover and watch them at feeding.
- Eastern Betta may hunt Lambchop Rasbora, fry or shrimplets — safest in a heavily planted tank.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Humpbacked Tetra⚠️ With cautionSemi-aggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
- Humpbacked Tetra clearly outsizes Lambchop Rasbora and is semi-aggressive; risky unless the tank is big and well-planted.
- Humpbacked Tetra may hunt Lambchop Rasbora, fry or shrimplets — safest in a heavily planted tank.
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Lambchop Rasbora 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 cautionPeaceful · 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 Lambchop Rasbora 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.
- Rainbow Emperor Tetra⚠️ With cautionSemi-aggressive · 3.6 cm · Medium care · 22–28 °C (72–82 °F)
- Rainbow Emperor Tetra and Lambchop Rasbora are close in size, but the semi-aggressive one tends to dominate — add lambchop rasbora in a group to spread the pressure.
- Keep Lambchop Rasbora 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.
- Serpae Tetra⚠️ With cautionSemi-aggressive · 4 cm · Easy care · 23–28 °C (73–82 °F)
- Serpae Tetra is semi-aggressive and may chase or nip the smaller Lambchop Rasbora — plant heavily and break up sight lines.
- Keep Lambchop Rasbora 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 cautionSemi-aggressive · 5 cm · Easy care · 22–28 °C (72–82 °F)
- Expect Silvertip Tetra to harass Lambchop Rasbora at times; give dense cover and watch them at feeding.
- Keep Lambchop Rasbora 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 cautionSemi-aggressive · 5 cm · Medium care · 23–28 °C (73–82 °F)
- Spotfin Betta clearly outsizes Lambchop Rasbora and is semi-aggressive; risky unless the tank is big and well-planted.
- Spotfin Betta may hunt Lambchop Rasbora, fry or shrimplets — safest in a heavily planted tank.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Striped Red-Eye Puffer⚠️ With cautionAggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
- Striped Red-Eye Puffer is aggressive and may chase or nip the smaller Lambchop Rasbora — plant heavily and break up sight lines.
- Striped Red-Eye Puffer may hunt Lambchop Rasbora, fry or shrimplets — safest in a heavily planted tank.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Tiger Badis⚠️ With cautionSemi-aggressive · 4 cm · Medium care · 22–24 °C (72–75 °F)
- Tiger Badis and Lambchop Rasbora are close in size, but the semi-aggressive one tends to dominate — add lambchop rasbora in a group to spread the pressure.
- Keep Lambchop Rasbora in a shoal of 6+ or it gets stressed and nippy.
- Wine Red Betta⚠️ With cautionAggressive · 5 cm · Medium care · 24–28 °C (75–82 °F)
- Wine Red Betta clearly outsizes Lambchop Rasbora and is aggressive; risky unless the tank is big and well-planted.
- Wine Red Betta may hunt Lambchop Rasbora, fry or shrimplets — safest in a heavily planted tank.
- Keep Lambchop 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 3 cm Lambchop Rasbora whole.
- Alligator Gar is aggressive and may chase or nip the smaller Lambchop 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 Lambchop 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)
- Lambchop Rasbora is bite-sized to a 90 cm predatory clown knifefish — it will be eaten.
- Clown Knifefish clearly outsizes Lambchop Rasbora 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 Lambchop 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)
- Lambchop Rasbora 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 Lambchop 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 Lambchop 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)
- Koi (90 cm) is big enough to swallow the 3 cm Lambchop Rasbora whole.
- Your 75 L tank is below the ~3800 L this pairing really wants — crowding raises aggression.
- Keep Lambchop 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)
- Lambchop Rasbora is bite-sized to a 120 cm predatory redtail catfish — it will be eaten.
- Redtail Catfish is aggressive and may chase or nip the smaller Lambchop 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 Lambchop 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)
- Spotted Gar (90 cm) is big enough to swallow the 3 cm Lambchop Rasbora whole.
- Spotted Gar clearly outsizes Lambchop 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 Lambchop 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)
- Lambchop Rasbora 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 Lambchop Rasbora — plant heavily and break up sight lines.
- Your 75 L tank is below the ~20000 L this pairing really wants — crowding raises aggression.
- Keep Lambchop 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 3 cm Lambchop Rasbora whole.
- Wolf Cichlid clearly outsizes Lambchop Rasbora 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 Lambchop 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.
Lambchop Rasbora care specs
- Care level
- Medium
- Breeding
- Hard
- Max size
- 3 cm (1.2 in)
- Min tank size
- 60 L (15.9 gal)
- Temperature
- 23–28 °C (73–82 °F)
- pH
- 5.5–7
- Hardness
- 1–10 dGH
- Lifespan
- 3–5 years
- Diet
- Omnivore
- Swim level
- Middle
- Group size
- 6+ (shoaling)
- Family
- Cyprinidae
- Origin
- Southeast Asia — Thailand, Cambodia and the Malay Peninsula in slow, peat-stained forest streams
What is a Lambchop Rasbora?
The lambchop rasbora (Trigonostigma espei) is a small, shoaling cyprinid from Southeast Asia that punches well above its weight in colour and movement. Maxing out at around 3 cm (1.2 in), it carries a vivid copper-orange body set against a distinctive dark, elongated wedge — the “lambchop” blotch that runs from roughly mid-body to the base of the tail. Unlike the stockier harlequin rasbora (T. heteromorpha), the lambchop is slim and streamlined, giving the school a quicksilver quality in a planted aquarium.
Despite its delicate appearance, a group of six or more lambchop rasboras in a well-maintained, appropriately soft-water tank is a confident, active display. They are one of the best nano schooling options available: small enough for a 60 L (16 gal) tank, peaceful enough for mixed communities, and striking enough to be a genuine centrepiece species.
Where do Lambchop Rasboras come from?
Lambchop rasboras are native to Thailand, Cambodia, and the Malay Peninsula, where they inhabit slow-moving, heavily shaded forest streams and blackwater pools. These habitats are defined by leaf litter and decomposing plant matter that stain the water amber with tannins, dropping the pH well below neutral and keeping hardness extremely low. Light is filtered through a dense forest canopy, and aquatic vegetation and submerged roots provide cover and spawning sites.
Understanding this origin is essential to providing good care. Recreating even a soft approximation of those conditions — soft, acidic, warmly coloured water with plenty of plant cover — will keep lambchop rasboras healthier and more vividly coloured than hard, alkaline tap water ever will.
What size tank does a Lambchop Rasbora need?
The minimum practical tank is 60 litres (16 gallons). At 3 cm the fish itself is tiny, but lambchop rasboras are obligate shoalers and need a group of at least six — which means swimming space for the whole school matters. A 60 L tank gives a group of six to eight fish room to move, form a natural pecking order within the school, and exhibit their characteristic mid-water darting behaviour.
Longer, shallower tanks are preferable to tall ones because lambchop rasboras are middle-column swimmers and benefit from horizontal swimming distance. A 75–90 L (20–24 gal) long-format tank is an excellent target if space allows. Planted tanks with areas of open water flanked by stems and broad-leafed plants like Anubias or Cryptocoryne suit them perfectly. A dark substrate and some floating plants to diffuse the light will draw out their best colour.
What water parameters do Lambchop Rasboras need?
- Temperature: 23–28 °C (73–82 °F)
- pH: 5.5–7.0; the lower half of that range (pH 6.0–6.8) is where they truly thrive
- Hardness: 1–10 dGH; aim for the softer end wherever possible
Soft, slightly acidic water is not optional for long-term health — it mirrors the peat-forest streams they come from. In areas with hard tap water, consider using RO water blended back to 2–6 dGH, or add natural tannin sources: Indian almond leaves, catappa bark, or a small bag of aquarium peat in the filter all help lower pH and soften the water gently while adding the amber hue these fish are accustomed to.
Keep the current gentle — a spray bar pointed at the glass or a sponge filter provides turnover without blasting the school around. Stability is as important as hitting the right numbers: avoid rapid swings in temperature or chemistry.
What do Lambchop Rasboras eat?
Lambchop rasboras are omnivores with a small mouth to match their small body. The staple diet should be a quality nano flake or micro-pellet sized to fit comfortably in their mouths — standard flake is often too large and leads to wasted food that fouls the water.
Supplement the staple two to three times a week with small live or frozen foods: baby brine shrimp, daphnia, micro worms, or finely chopped bloodworm. These additions improve colour, condition the fish for potential breeding, and reflect the insect larvae and zooplankton they would encounter in the wild. Feed small amounts once or twice daily — only what the school can consume in two to three minutes — and remove any uneaten food promptly to keep water quality high.
Are Lambchop Rasboras aggressive — and what fish can live with them?
Lambchop rasboras are entirely peaceful and present no aggression to tank-mates of any kind. Their only real defence is the school itself: a tight, fast-moving group is harder for a predator to single out. This also means they are vulnerable to any fish large enough to eat them or nippy enough to harass them.
Good community companions share similar water requirements and a calm disposition. Dwarf gouramis (used sparingly), corydoras, otocinclus, small loaches, other nano rasboras, and peaceful dwarf cichlids like Apistogramma (with care taken around the rasbora’s size) are all workable. Avoid any fish above roughly 6–8 cm that could view the rasboras as food, and any known fin-nippers. Shrimp — including cherry and Amano shrimp — coexist well with lambchop rasboras because the fish are too small to pose a real threat to adult shrimp.
For a detailed, filterable list of tested pairings, see Lambchop Rasbora tank mates.
How do you tell male and female Lambchop Rasboras apart?
Sexing lambchop rasboras requires a close look, especially on younger fish. Females are slightly larger and develop a noticeably rounder, deeper belly, particularly when gravid (carrying eggs). The key diagnostic is the dark lambchop blotch: on males, the lower edge of the blotch curves downward to a more pronounced point; on females, the lower edge is softer and more rounded, without the sharp downward extension. Both sexes display the same copper-orange ground colour, though well-conditioned females often appear somewhat paler overall. In a mixed group, the combination of body depth and blotch shape together gives the clearest read.
How do Lambchop Rasboras breed?
Lambchop rasboras are egg depositors that spawn on the undersides of broad leaves in a style similar to their harlequin relatives — but earning a “hard” breeding difficulty rating for good reason. Triggering spawning reliably demands very soft, acidic water (pH 5.5–6.5, hardness 1–5 dGH) that many home tap supplies cannot reach without reverse osmosis or similar treatment.
Condition a small group or a chosen pair for several weeks on live and frozen foods before attempting a dedicated breeding setup. A bare-bottom tank of 30–40 L with a sponge filter, dim lighting, and several broad-leafed plants (Anubias nana works well) is the typical approach. If conditions are right, the male courts the female with a shimmy-and-circle display before they turn upside-down together beneath a leaf to deposit and fertilise a small number of adhesive eggs. The parents offer no parental care and will eat eggs if left in the tank; remove them after spawning.
Eggs hatch in roughly 24–36 hours and fry become free-swimming a few days later. The fry are tiny and require infusoria or commercial micro-fry foods for the first week or two before graduating to baby brine shrimp nauplii. Expect small clutches and be prepared for several failed attempts before conditions align correctly.
What are common Lambchop Rasbora diseases?
Lambchop rasboras kept in appropriate soft, acidic water are reasonably hardy, but their small size means they can decline quickly once illness takes hold. Watch for:
- Ich (white spot): Fine white granules across the body and fins — the classic aquarium disease. Usually triggered by temperature swings or introducing fish from unconditioned water. Prevention: stable temperature, proper quarantine of new arrivals.
- Velvet: A dusty, gold or rust-coloured sheen, often accompanied by flicking or scratching. More common in fish stressed by poor water chemistry. Prevention: correct soft, acidic water parameters and low stress.
- Fin rot: Ragged or receding fin edges, almost always tracing back to water quality. Prevention: regular water changes, avoiding overstocking, keeping nitrates low.
- Bacterial infections / wasting: Lambchop rasboras can be susceptible to internal parasites and wasting diseases, particularly when sourced from farms keeping them in inappropriate water. Prevention: buy from reputable suppliers, quarantine for two to four weeks before adding to the main tank, and watch for failure to thrive or visible thinning around the belly.
Health note: Disease identification in small fish can be challenging, and symptoms often overlap between conditions. Confirm what you are seeing against a reputable veterinary or fish-health source before reaching for any treatment.
How long do Lambchop Rasboras live?
A well-cared-for lambchop rasbora lives 3–5 years. Reaching the upper end of that range requires consistently good water quality — particularly soft, appropriately acidic conditions — a varied diet, and a stable, stress-free environment with a proper shoal of six or more companions. Fish kept in hard, alkaline water or as isolated individuals rarely reach their potential lifespan. Buy healthy stock from a reputable source, quarantine before introducing to your main tank, and these vivid little fish will reward you with years of active, colourful schooling behaviour.
Frequently asked questions
How is the lambchop rasbora different from the harlequin rasbora?
The lambchop (Trigonostigma espei) is noticeably slimmer and a centimetre or two smaller than the harlequin (T. heteromorpha). Its dark blotch is also thinner and more elongated — earning the 'lambchop' nickname — and it prefers softer, more acidic water. In a well-lit planted tank the coppery orange on the body is just as vivid, but the overall silhouette is more streamlined and delicate.
Why are lambchop rasboras hard to breed?
They spawn like their relatives — depositing eggs on the undersides of broad leaves — but are notoriously fussy about water chemistry. Very soft (1–5 dGH), acidic (pH 5.5–6.5) water is usually needed to trigger spawning, and mature fish aged a year or more are better candidates than juveniles. Condition the group with small live or frozen foods for several weeks before attempting. Even with ideal conditions the clutch is small and the fry are tiny and require infusoria or commercial first foods.
What you need to keep a lambchop rasbora
The baseline is a heated, filtered 60 L+ tank: a reliable heater to hold 23–28 °C (73–82 °F), a gentle filter that won't batter a lambchop rasbora in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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