What size tank does a Harlequin Rasbora need?

Harlequin Rasbora needs a minimum of 10 gallons, with 20 gallons recommended. They are middle swimmers. Keep in groups of 6+.

Is Harlequin Rasbora good for beginners?

Harlequin Rasbora is rated "beginner" difficulty (1/5). Great for beginners.

What fish are compatible with Harlequin Rasbora?

Harlequin Rasbora is peaceful. Compatible tank mates include other peaceful fish with similar water parameters (pH 6-7.5, temp 72-81°F).

Harlequin Rasbora

Trigonostigma heteromorpha

Family: Cyprinidae • Origin: Southeast Asia

The Harlequin Rasbora is a classic community fish with a distinctive triangular black patch on copper-orange body. Hardy and peaceful.

Min Tank

10 gal

Max Size

Temperature

72-81°F

6-7.5

Lifespan

6 years

School Size

Swim Level

middle

Hardness

2-12 dGH

peacefulbeginneromnivoreschooling

Is Harlequin Rasbora Right for Your Tank?

Harlequin Rasbora is an excellent choice for beginners — rated "beginner" difficulty (1/5). They're hardy, forgiving of minor water parameter fluctuations, and generally easy to feed. At just 10 gallons minimum, they work well in nano tanks and smaller setups.

With a peaceful temperament, Harlequin Rasbora makes a great community fish. They coexist well with other non-aggressive species of similar size. This is a schooling species — keep at least 6 together, or they may become stressed and display abnormal behavior. Expected lifespan: 6 years with proper care.

Common Mistakes with Harlequin Rasbora

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Keeping fewer than 6 together

Harlequin Rasbora is a schooling species — they need a group of at least 6 to feel secure. Lone or paired individuals become stressed, hide constantly, and may develop health issues or aggression.

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Relying on a heater without a thermometer

Harlequin Rasbora needs 72–81°F. Heaters malfunction or drift over time — always use a separate thermometer to verify. Temperature swings of even 3–4°F can trigger stress and disease, particularly ich.

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Putting them in a tank under 10 gallons

While 10 gallons is the minimum, nano tanks require more frequent water changes and leave less room for error. A slightly larger tank (20 gal) is much more forgiving.