Crimson-spotted Rainbowfish Breeding Guide

How to breed Melanotaenia duboulayi, an Australian rainbowfish; a pairing plant-spawner whose adhesive eggs attach to fine vegetation over several days.

Overview

Melanotaenia duboulayi is a rainbowfish endemic to coastal river systems east of the Great Dividing Range in northeastern New South Wales and southeastern Queensland, Australia, according to Wikipedia. Males reach about 11-12 cm and are larger and more colourful than females. It is an egg-scattering plant spawner.

Sexing

Wikipedia notes that males display brighter coloration and elongated fin rays, which become especially marked during spawning when the fins turn intensely black; females are generally smaller and plainer. A bonded pair or trio with extra females is typical for breeding.

Conditioning

The species is omnivorous. Conditioning a group on a varied diet, then setting up a pair or small group, brings the fish into spawning readiness. FishBase reports breeding takes place across a temperature range of about 16-28 C.

Breeding Setup

FishBase lists a tolerated pH of about 5.4-7.8 for the species. Spawning is carried out over fine-leaved plants, spawning mops or floating plant roots, which provide attachment sites for the adhesive eggs.

Spawning Behavior & Trigger

According to Wikipedia, spawning occurs prior to the summer rains and the eggs adhere to filamentous subsurface vegetation and floating plant roots. FishBase describes the species as forming distinct pairs during reproduction; eggs are released over a period rather than all at once.

Egg & Fry Care

The adhesive eggs hang on the vegetation or mops and can be moved to a separate container to protect them from being eaten. Once the fry become free-swimming they require very fine first foods such as infusoria or commercial fry food before progressing to Artemia nauplii. Detailed incubation times are not given in the consulted sources and are therefore omitted.

Common Challenges

Because eggs and fry are scattered over plants rather than guarded, removing egg-laden mops protects them from predation. The tiny first-feeding fry need very small foods, the main bottleneck in raising rainbowfish.