Three-lined Pencilfish Breeding Guide

Breeding the three-lined pencilfish (Nannostomus trifasciatus): sexing, an egg-scattering free spawner over fine plants or mesh in soft water, and rearing tiny fry.

Overview

The three-lined pencilfish, Nannostomus trifasciatus, is an egg-scattering free spawner exhibiting no parental care. It will spawn frequently in mature aquaria with minimal intervention, though a dedicated setup gives more dependable results.

Sexing

Adult males are more intensely coloured, especially when in spawning condition, while females are noticeably rounder-bodied.

Conditioning

Condition the adults together, then move a single pair, or a group of one or two males with several females, into the breeding container. Keeping the breeding group small helps reduce egg predation.

Breeding Setup

Use a dimly lit tank with mature water. Cover the base with mesh, plastic grass matting or glass marbles so the eggs can fall out of reach, or fill much of the tank with a fine-leaved plant such as Taxiphyllum or spawning mops. An air-powered sponge filter provides oxygenation. Slightly acidic to neutral water with a temperature towards the upper end of the 22-28 degrees C range suits spawning.

Spawning Behavior & Trigger

The fish scatter eggs freely over the medium, with eggs settling through the mesh or among the fine plants. The more individuals involved, the greater the risk of egg predation, so the breeding group is kept small.

Egg & Fry Care

Remove the adults after two to three days; the first fry should be visible around three days later. Start them on Paramecium or a proprietary dry food of 5-50 micron grade, progressing to Artemia nauplii and microworm once they are large enough.

Common Challenges

This species is more aggressive than most of its relatives, with territorial males, so spacious breeding quarters with visual barriers help, and groups of ten or more spread aggression. As with all pencilfishes, the tiny fry depend on densely available micro-foods at first.