Harlequin rasbora

Trigonostigma heteromorpha

FreshwaterFish

Care at a glance

Temperature: 72–82°F; 22–28°C
pH: 6.0–7.0
Adult size: 2 in; 5 cm
Minimum tank: 15 gal; 55 L

Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Beginner
Breeding: Egg depositor · Medium
Rarity: Common
Family: Cyprinidae
Origin: Thailand, Sunda Islands

Overview

The harlequin rasbora is a small, peaceful schooling fish for the middle of a community tank. It is calm, easy to keep and a good first fish.

Did you know

A female harlequin rasbora flips belly-up to lay her eggs.

Caring for the harlequin rasbora

Keep harlequin rasboras in a school of at least six, and more if the tank allows, in 15 gal (55 L) or more. Give them a dim tank with plenty of plants, some driftwood and a soft sand substrate. Tannin-stained water from botanicals suits them and brings out their color.

They like soft, warm water, at 72 to 82°F (22 to 28°C) and a pH of 6.0 to 7.0. They eat just about anything small, such as good flake, micro-pellets and frozen or live bloodworms and daphnia.

They are peaceful and spend most of their time in the middle of the water column, moving as a tight group. They make calm community fish with other peaceful species that like the same soft, warm water.

Harlequin rasboras spawn only on the underside of a broad leaf, sticking their eggs there, which is unusual for a rasbora. They are one of the harder small egg-layers to breed at home, since they need very soft, acidic water.

Good to know

The harlequin rasbora is a small cyprinid in the family Cyprinidae. The big black triangle on the rear half of its body is its trademark. The species is listed as Least Concern, with stable wild populations.

In the wild

Harlequin rasboras come from slow, soft, acidic blackwater streams in Thailand and the Sunda Islands. These streams are shaded by trees and full of leaf litter and roots.

Weekly picks

Tank mates

The harlequin rasbora is a peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a harlequin rasbora need?

A harlequin rasbora needs at least 15 gal (55 L). It spends most of its time in the middle.

What temperature and pH does a harlequin rasbora need?

A harlequin rasbora is comfortable at 72–82°F (22–28°C) with a pH of 6.0–7.0.

What does a harlequin rasbora eat?

A harlequin rasbora eats just about anything small, such as good flake and micro-pellets. Frozen or live bloodworms and daphnia suit it as well.

How big does a harlequin rasbora get?

An adult harlequin rasbora reaches about 2 in (5 cm).

Does a harlequin rasbora need a group?

Yes. A harlequin rasbora is a schooling species and should be kept in a group, not singly.

How does a harlequin rasbora breed?

Harlequin rasboras spawn only on the underside of a broad leaf, where they stick their eggs. They are one of the harder small egg-layers to breed, since they need very soft, acidic water.