Harlequin Rasbora
Trigonostigma heteromorpha
Minimum Tank
10 Gallons
Adult Size
2 inches
Temperature
72-81°F (22-27°C)
pH Range
6.0-7.5
Lifespan
6 years
School Size
8+ fish
About Harlequin Rasbora
The harlequin rasbora is a graceful, copper-toned schooling fish native to the peat swamp forests and blackwater streams of Malaysia, Singapore, Sumatra, and Thailand. Its most distinctive feature is the dark, triangular or lamb-chop-shaped patch on the rear half of its body, set against a warm pinkish-copper background. Harlequin rasboras are true schooling fish that swim in tight, coordinated formations, creating a mesmerizing display of synchronized movement. They are among the most popular and widely available rasbora species in the aquarium trade. In the wild, they spawn by depositing eggs on the undersides of broad leaves, a behavior they will replicate in the aquarium with plants like cryptocorynes.
Care Requirements
Tank Setup
- • Minimum 10-gallon tank required
- • Temperature: 72-81°F (22-27°C)
- • pH: 6.0 - 7.5
- • Category: Rasbora
Diet & Feeding
- • Diet type: Omnivore
- • Feed 1-2 times daily
- • Varied diet recommended
Tank Mate Compatibility
Compatible With
Avoid Keeping With
Care Tips
Expert Tips
Keep harlequin rasboras in groups of at least eight, as they are most confident and active in larger schools. They prefer soft, slightly acidic water at 73-82°F with subdued lighting and plenty of plants. A dark substrate and tannin-stained water bring out the richest coloring. These rasboras are peaceful and make ideal companions for other gentle community fish, dwarf shrimp, and small corydoras. Feed quality micro-pellets and flakes supplemented with frozen daphnia and brine shrimp. They are generally hardy once established but can be sensitive during initial acclimation, so drip-acclimate new fish slowly over at least an hour.
Quick Facts
38L
Min Tank (10gal)
5cm
Adult Size (2")
6yr
Lifespan
8+
Min School
Build Your Perfect Community Tank
Find compatible tankmates for your Harlequin Rasbora
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Tank Mates for Harlequin Rasbora
Species from our database with overlapping water parameters, compatible temperaments and a realistic shared tank size.
Dwarf Gourami
Trichogaster lalius
moderate · 10+ gal
Honey Gourami
Trichogaster chuna
easy · 10+ gal
Julii Corydoras
Corydoras julii
easy · 15+ gal
Panda Corydoras
Corydoras panda
easy · 10+ gal
Similar Care Level
Other easy-care species that suit a comparable setup.
Frequently Asked Questions
What size tank does a Harlequin Rasbora need?
A Harlequin Rasbora needs a minimum tank size of 10 gallons (38 litres). They should be kept in schools of at least 8.
What water parameters does a Harlequin Rasbora need?
Harlequin Rasbora thrive in water between 72-81°F (22-27°C) with a pH of 6.0-7.5.
Are Harlequin Rasbora easy to care for?
Harlequin Rasbora are considered easy to care for. They are peaceful fish with a lifespan of about 6 years.
How big do Harlequin Rasbora get and what do they eat?
Harlequin Rasbora reach about 2 inches and are omnivores. Keep harlequin rasboras in groups of at least eight, as they are most confident and active in larger schools. They prefer soft, slightly acidic water at 73-82°F with subdued lighting and plenty of plants. A dark substrate and tannin-stained water bring out the richest coloring. These rasboras are peaceful and make ideal companions for other gentle community fish, dwarf shrimp, and small corydoras. Feed quality micro-pellets and flakes supplemented with frozen daphnia and brine shrimp. They are generally hardy once established but can be sensitive during initial acclimation, so drip-acclimate new fish slowly over at least an hour.