What Size Tank Does a Harlequin Rasbora Need?
Minimum tank: 10 gallons
A Harlequin Rasbora (Trigonostigma heteromorpha) grows to about 1.8 in (4.6 cm), so the practical minimum is a 10-gallon aquarium. Because the Harlequin Rasbora is a schooling fish, keep at least 6 together — a shoal needs more swimming room than one fish, so size up for a full group plus tankmates.
| Single fish or pair | 10 gallons |
|---|---|
| Comfortable group | 20 gallons |
| Community setup | 20 gallons+ |
Bigger is easier: more water dilutes waste and holds temperature and pH steady. See stocking ideas for a 10-gallon tank or try the stocking calculator.
Frequently asked questions
What is the minimum tank size for a Harlequin Rasbora?
At least 10 gallons. Keep a group of 6+, which prefers something larger.
Can a Harlequin Rasbora live in a smaller tank?
Going under 10 gallons stresses the fish, worsens water quality and shortens its life — not recommended.
More on this species: Harlequin Rasbora full care guide · tank size · temperature · pH & hardness · tank mates