Exclamation-point rasbora

Boraras urophthalmoides

Also known as Least rasbora

FreshwaterFish

Exclamation-point rasbora (Boraras urophthalmoides) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 73–81°F; 23–27°C
pH: 6.0–7.0
Adult size: 0.6 in; 1.6 cm
Minimum tank: 11 gal; 40 L

Temperament: Peaceful
Social behavior: Shoaling
Swim level: Middle
Difficulty: Medium
Breeding: Egg scatterer · Medium
Rarity: Common
Family: Cyprinidae
Origin: Southeast Asia (Thailand, Cambodia, Vietnam)

Overview

The exclamation-point rasbora is a tiny, peaceful shoaling fish for a planted tank of soft water. It suits a keeper with some experience.

Did you know

The exclamation-point rasbora is named for the marking near its tail. A thin dark stripe ends in a round spot at the tail base. Together they look like an exclamation point lying on its side.

Caring for the exclamation-point rasbora

Keep exclamation-point rasboras in a school of 8 to 10 or more, in a tank of at least 11 gal (40 L). A small group hides and loses its color. Give them a mature, heavily planted tank with driftwood, gentle flow and dim light. They hold their best color over a dark substrate in low light.

Keep the water soft and slightly acidic, at 73 to 81°F (23 to 27°C) and a pH of 6.0 to 7.0. A few catappa leaves tint the water and soften it. Feed tiny foods their small mouths can manage, such as crushed micro pellets, baby brine shrimp and microworms.

Exclamation-point rasboras are peaceful shoalers of the middle water. They drift through open space near the plants and warm up to a tank as they settle in. They are shrimp-safe, so pair them only with other small, calm species, and skip anything big enough to bully or eat them.

They scatter their eggs and give no parental care. Breeding them is doable but takes patience.

Good to know

The exclamation-point rasbora, Boraras urophthalmoides, is a tiny cyprinid in the family Cyprinidae and one of the smallest fish in the trade. It also goes by least rasbora. Most are wild caught, and they are often sold mixed in with, or mislabeled as, the chili rasbora, Boraras brigittae. Mixed groups of the two are common in stores, and you sometimes sort out which is which only once they color up at home.

In the wild

Exclamation-point rasboras come from slow, shallow blackwater in Thailand, Cambodia and Vietnam. They live in forest pools and ditches stained dark with tannins and packed with plants.

Weekly picks

Tank mates

The exclamation-point rasbora is a peaceful, shoaling 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