Vaillant's Chocolate Gourami Breeding Guide

How to breed Sphaerichthys vaillanti, a Bornean blackwater gourami that is a paternal mouthbrooder, with the male carrying eggs and fry for one to three weeks.

Overview

Sphaerichthys vaillanti is a small osphronemid gourami from Borneo, reaching about 45-55 mm standard length according to Seriously Fish. Unlike most labyrinth fish it is a paternal mouthbrooder: the male incubates the eggs in his mouth rather than building a bubble nest. It is a blackwater species kept in soft, acidic conditions.

Sexing

Seriously Fish notes that females have a uniformly straight lower jaw and a more pointed head shape, while males show a slightly rounded lower jaw caused by distensible skin that expands during mouthbrooding. When acclimatised, females display red and green patterning that intensifies during courtship, whereas males remain brownish.

Conditioning

The species is carnivorous and benefits from a varied diet of small live and frozen foods to bring adults into condition before spawning. A stable, mature blackwater set-up is important for this demanding fish.

Breeding Setup

A base footprint of at least 60 x 30 cm is recommended by Seriously Fish. Spawning is carried out in soft, acidic water; the species is maintained at 21-25 C with a pH of 3.5-6.5 and very low hardness (0-54 ppm). Subdued lighting and tannin-stained water suit the fish.

Spawning Behavior & Trigger

Courtship is normally initiated by the female, or the alpha female where several are present. During the spawning embrace the pair remains almost upright, which is unusual among gouramis. According to Seriously Fish the process may take several hours, with eggs laid and fertilised on the substrate and the male collecting them directly into his mouth; both fish defend the surrounding area.

Egg & Fry Care

The male broods the developing eggs and fry in his mouth for 7-20 days. He then releases 10-40 fully formed, free-swimming juveniles, which immediately take live foods such as microworm or Artemia nauplii. Seriously Fish advises daily water changes of around 10 percent and a tightly fitting cover, since the fry need a layer of warm, humid air for proper development of the labyrinth organ.

Common Challenges

The main difficulties are maintaining the extremely soft, acidic water this species requires and avoiding disturbing the brooding male, which may swallow or spit out the brood if stressed. Stable, low-flow blackwater conditions are essential for success.