The harlequin rasbora is a peaceful shoaling fish from the soft, acidic forest streams and peat swamps of Southeast Asia.
Its warm copper-pink body and black triangular patch make a dense shoal an attractive sight in a planted community tank.
Hardy, long-lived and captive-bred, it is a good beginner fish that adapts well once a tank is cycled.
It rewards patience with years of reliable colour and calm behaviour in the right soft-water setup.
Housing
Keep a shoal of eight to ten or more in 60 litres (15 gallons) or larger, filtered and heated to 23-27C.
They look best against dark substrate in a planted, dimly lit tank with driftwood and light tannin staining that echoes their native swamps.
They prefer soft, slightly acidic water but adapt to moderately hard supplies if kept stable.
Provide gentle flow, open midwater swimming space and planted cover so the shoal feels secure enough to display full colour.
Diet
Harlequins are easy omnivores with small mouths.
A quality micro-pellet or flake forms a dependable staple, rotated with frozen or live daphnia, baby brine shrimp, cyclops and finely chopped bloodworm for variety and condition.
Feed small amounts once or twice daily, only what is consumed within a minute or two.
Varied feeding supports their colour and the general health that helps them reach their long lifespan.
Health
Harlequins are robust and disease-resistant, with most problems traceable to chilling, poor water quality or stress rather than weak stock.
Ich and fin rot are the usual concerns and respond quickly to corrected conditions and prompt treatment.
Stable warmth, soft water and weekly partial changes prevent the majority of issues.
Quarantine new arrivals, acclimatise gently, and keep them in a settled, well-cycled tank, where they prove trouble-free over many years.
Temperament
Peaceful, social and tightly shoaling when kept in good numbers, harlequins glide calmly through midwater and rarely trouble their tankmates.
A larger group settles faster, colours up and swims more openly.
They are good community fish alongside other gentle soft-water species such as small tetras, corydoras, dwarf cichlids and shrimp.
Avoid large, boisterous or predatory tankmates that intimidate the shoal or keep these mild fish hiding among the plants.
Beginner
Beginner
Beginner
Beginner
Beginner
Beginner