Coral Red Pencilfish Breeding Guide

Breeding the coral red pencilfish (Nannostomus mortenthaleri): sexing by the male's red colour, spawning over fine plants or mops in soft acidic water, and rearing the fry.

Overview

The coral red pencilfish, Nannostomus mortenthaleri, is a small, vividly coloured species that can be spawned in heavily planted tanks. Like other pencilfishes it is an egg-scattering spawner without parental care, and the eggs benefit from a fine spawning medium that keeps them out of the adults' reach.

Sexing

Adult males are noticeably less stocky and far more colourful than females, and only males display the bright red body coloration. Males also show a white marking at the anterior dorsal-fin base from quite a young age, making the sexes easy to tell apart.

Conditioning

The adult group can be conditioned together, while one or more smaller containers are set up and filled with aged water for spawning. Good condition in the breeders improves both spawning frequency and egg quality.

Breeding Setup

Provide a spawning medium of fine wool mops, Taxiphyllum or another fine-leaved aquatic plant in aged water. The species' soft, acidic preferences should be matched, with a temperature of 24-28 degrees C, pH 4.0-7.0 and hardness 18-90 ppm.

Spawning Behavior & Trigger

After the conditioned fish are introduced to the breeding container, they scatter eggs into the fine plants or mops. The adults can be removed after two to three days.

Egg & Fry Care

The first fry should be visible a day or two after the adults are removed. Start them on Paramecium or a proprietary dry food of 5-50 micron grade, introducing Artemia nauplii and microworm once the fry are large enough. Adult patterning develops after about eight weeks.

Common Challenges

Males are aggressive toward rivals, and in confined quarters serious injury or even death can occur, so spawning is usually done with carefully chosen individuals or by keeping larger groups of ten or more to spread aggression. As with all pencilfishes, supplying suitably tiny first foods is essential for the small fry.