Red Rainbowfish (Glossolepis incisus) Breeding Guide

Breeding Glossolepis incisus: select the fattest pair, daily thread-attached eggs on plants or mops over weeks, removing eggs to a rearing tank, and sensitive fry care.

Overview

Glossolepis incisus is native to Lake Sentani in northern New Guinea and reaches about 15 cm standard length. It is quite easy to breed, laying eggs over an extended period onto fine-leaved plants or spawning mops.

Sexing

Mature males develop a much higher back than females, and only males develop the characteristic red colouration that gives the fish its common name. Temperature affects colour: at slightly lower temperatures all males turn red, whereas in warmer water only the dominant fish tend to do so.

Conditioning

The adults are best conditioned in a group in a separate aquarium with plenty of live and frozen foods. Once conditioned, select the fattest pair for spawning and introduce them to the spawning tank.

Breeding Setup

Use a spawning tank of at least about 75 cm in length with slightly hard, alkaline water around pH 7.5 and a temperature of roughly 21-24 °C. Include fine-leaved plants or spawning mops and a small air-powered filter.

Spawning Behavior & Trigger

The pair spawn over a period of several weeks, laying a few eggs each day. The eggs are attached to surfaces such as the plants or mops by a small thread.

Egg & Fry Care

The eggs hatch in 7-8 days. Remove the eggs daily to a separate rearing tank. The fry initially require infusoria-type foods, graduating to microworms or brine shrimp nauplii after one week. They are quite sensitive to unfavourable water conditions, so frequent small water changes are essential.

Common Challenges

Daily transfer of egg-laden mops to a rearing tank is the practical key to good yields, preventing the eggs being eaten. Because the fry are sensitive to water quality, maintaining clean, stable water with frequent small changes is the main ongoing demand.