Harlequin rasbora
Trigonostigma heteromorpha
Copper-orange schooling fish with a black wedge; hardy, calm and a good first school for a 15–20 gallon tank.
Key facts
- Body length
- 1.4 in without fins
- Minimum tank
- 17 gallons
- Group
- 8+
- Temperament
- Peaceful
- Care level
- 1 / 5
- Lifespan
- 5–8 years
- Diet
- Flakes, micro pellets, frozen bloodworm and daphnia
- Origin
- Malaysia, Singapore, Sumatra and southern Thailand
- Hardier than87%
- Bigger than12%
- Calmer than68%
Water: their range vs yours
Harlequin rasbora tank mates
- Neon tetraGets along in shared water.Good mates
- Fancy guppyGets along in shared water.Good mates
- Panda corydorasGets along in shared water.Good mates
- OtocinclusGets along in shared water.Good mates
- Cherry shrimpGets along in shared water.Good mates
- BettaGets along in shared water.Good mates
- Amano shrimpGets along in shared water.Good mates
- Black neon tetraGets along in shared water.Good mates
- Black widow tetraGets along in shared water.Good mates
- Blood parrot cichlidGets along in shared water.Good mates
- Bristlenose plecoGets along in shared water.Good mates
- Bronze coryGets along in shared water.Good mates
- Tiger barbBarbs may harass rasboras.Risky
- Chinese algae eaterChinese algae eater attacks fish with a similar shape or colour: Harlequin rasbora.Risky
- Clown loachClown loach attacks fish with a similar shape or colour: Harlequin rasbora.Risky
- DemasoniDemasoni attacks fish with a similar shape or colour: Harlequin rasbora.Risky
- Golden mbunaGolden mbuna attacks fish with a similar shape or colour: Harlequin rasbora.Risky
- Peacock cichlidMalawi butterfly peacock attacks fish with a similar shape or colour: Harlequin rasbora.Risky
- AngelfishAngelfish can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 2.3 cm.Avoid
- Blue dolphin cichlidBlue dolphin cichlid can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 6.3 cm.Avoid
- Convict cichlidConvict cichlid can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 3.8 cm.Avoid
- Firemouth cichlidFiremouth cichlid can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 3.0 cm.Avoid
- GoldfishGoldfish can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 3.0 cm.Avoid
- Iridescent sharkIridescent shark can eat Harlequin rasbora: prey body depth 1.1 cm ≤ mouth 32.5 cm.Avoid
How we check
The numbers the tank model uses for harlequin rasboras: water as ideal and tolerated ranges, bioload from adult mass, space, flow and how they act on other species.
- Standard length
- 3.5 cm (SL)
- Adult mass
- 0.64 g
- Bioload at 25 °C
- 0.75 BU
- Min. water
- 54 L net
- Min. footprint
- 60 × 30 cm per group
- Group
- 8+ (best 10)
- Swims in
- middle, top
- Flow
- low
- Body / fins
- fusiform, normal fins
- Diet type
- micropredator
- Fin nipper
- none
- Sensitive to
- —
Care notes
Harlequins live in slow, plant-choked waters of Southeast Asia. They school loosely in the upper half of the tank and tolerate a wider pH range than most tetras.
They are gentle with almost everything their size. Shrimp adults are safe, but newborn shrimp will be eaten.
Questions
What size tank does a harlequin rasbora need?
At least 17 gallons (54 litres of water after decor). Adults reach about 1.4 inches without fins.
How many harlequin rasboras should be kept together?
Keep at least 8, ideally 10 or more: fewer feel exposed and hide or turn nippy.
What water do harlequin rasboras need?
73–81 °F, pH 6–7 and 1–12 dGH. Harlequin rasboras come from Malaysia, Singapore, Sumatra and southern Thailand.
How long do harlequin rasboras live?
5–8 years with good care.
What fish can live with harlequin rasboras?
Good tank mates include Neon tetra, Fancy guppy, Panda corydoras, Otocinclus and Cherry shrimp. Each is checked both ways for size, fin nipping, temperament, territory and shared water.