Brilliant Rasbora (Rasbora einthovenii) Breeding Guide

Rasbora einthovenii is an egg-scattering continuous spawner from Sundaland blackwater swamps, bred in dimly lit mesh-base tanks with cool, soft, acidic water.

Overview

Rasbora einthovenii, the brilliant rasbora, is a slim cyprinid from Southeast Asian blackwater swamps across Thailand, Peninsular Malaysia, Borneo and Sumatra, reaching about 9 cm. According to Seriously Fish it is an egg-scattering, continuous spawner that exhibits no parental care.

Sexing

Seriously Fish reports that mature females are noticeably rounder-bellied and often slightly larger than males. No other reliable external difference is documented.

Conditioning

The species is a micropredator preferring small live and frozen foods such as Daphnia and Artemia over an exclusively dried diet. Conditioning females until they appear full of eggs precedes a spawning attempt.

Breeding Setup

Seriously Fish recommends one or more shallow containers (about 75 x 30 x 30 cm) half-filled, very dimly lit, with mesh at the base that allows eggs to fall through but prevents adult access. An internal power filter can be added initially, positioned to direct flow lengthwise.

Spawning Behavior & Trigger

Water should be slightly acidic to neutral with temperature towards the upper end of the range (around 26 C). One or two pairs are introduced when females appear full of eggs, and spawning is initiated by adding cool water gradually and feeding live and frozen foods.

Egg & Fry Care

Incubation takes between 18 and 48 hours, with fry free-swimming 24-48 hours later. Initial food is Paramecium, progressing to Artemia nauplii and microworm as the fry grow.

Common Challenges

As with other scatterers, a mesh base or dense cover protects eggs from being eaten, and the small free-swimming fry need correctly sized first foods. Soft, acidic blackwater conditions best replicate the natural habitat.