Rasboras: Peaceful Shoaling Fish for Calm Tanks

Rasboras are small, calm shoaling fish from Asia. Keep at least five of one species in a heated, planted tank of at least about 12 gallons (45 liters) for the smallest species or 16 gallons (60 liters) for larger ones, at about 72–81°F (22–27°C). Feed small flake and frozen foods once a day, and choose peaceful tank mates.

Figures from the Ornamental Aquatic Trade Association (OATA)'s rasbora care sheet; check your species' needs with a specialist keeper or aquatics store.

Rasboras at a glance
Group	At least 5 of one species
Size	Most under 2 in (5 cm)
Tank	At least about 12 gallons (45 liters); 16 gallons (60 liters) for larger species
Temperature	72–81°F (22–27°C)
pH	6.5–8.0
Food	Flake or granules plus small frozen foods
Temperament	Calm and peaceful

Calm Shoalers From Asia

Rasboras are small, calm fish from south and southeast Asia. OATA lists around 70 species, though only a few are common in stores, and most for sale are captive bred and easy to keep. The harlequin rasbora, with its black triangle patch, is the classic choice for a peaceful community tank.

Tiny Boraras species, such as the chili rasbora, suit planted nano tanks. The galaxy rasbora (now classed as a danio) is shy and needs quiet company.

Shoal Size and Fish Size

Rasboras are social and OATA recommends groups of at least five, with more being better. Kept alone or in a small group, they often become stressed.

Only a few species grow over 2 inches (5 cm), so a shoal fits in a modest tank.

Tank and Water

OATA recommends at least about 12 gallons (45 liters) for a shoal of the smallest species and about 16 gallons (60 liters) for larger species of 2 inches (5 cm) or more.

Heater: about 72–81°F (22–27°C).
Plants: plenty of cover, especially for shy species, with open water to swim in.
Flow: a gentle current for small species.
Water: pH about 6.5–8.0, soft to medium hardness.

Setting Up for Rasboras

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Rasboras like a planted tank with soft light and a gentle filter. Add a heater, small foods and a test kit.

Feeding Rasboras

OATA suggests good-quality flake or granules, plus small live or frozen foods such as daphnia. Feed what they eat in a few minutes once a day. For tiny species, crush flake or use micro foods.

Tank Mates

Rasboras do well with other calm fish: small tetras, corydoras, otocinclus, peaceful gouramis and shrimp in larger tanks. Tiny species need tank mates too small to eat them, and timid species such as the galaxy rasbora shouldn't share with boisterous fish.

Keeping Them Healthy

Most problems in small fish start with water quality. Test ammonia, nitrite and nitrate weekly, change about a quarter of the water each week with conditioned tap water, and rinse filter media in old tank water, never under the tap. Quarantine new fish if you can, and add them a few at a time so the filter keeps up.

Watch your fish every day at feeding time. Changes in swimming, color, breathing or hiding are early signs that something is wrong, so test the water first.

For fish treatments or medicines: see your vet or a pet supply store with trained staff. An aquatics store with trained staff, or a vet who treats fish, can help you work out what's wrong before you add anything to the tank.

Frequently Asked Questions

What new keepers ask about rasboras.

How many rasboras should I keep?

At least five, according to OATA, and more is better.

Are harlequin rasboras good for beginners?

Yes. OATA notes harlequins suit most standard community tanks.

What size tank do chili rasboras need?

OATA suggests at least about 12 gallons (45 liters) for a shoal of the smallest species. Keep them with tank mates too small to eat them.

Do rasboras need a heater?

Yes. OATA suggests about 72–81°F (22–27°C).