Breeding Betta

How to breed Betta splendens: sexing, bubble-nest building by the male, the nuptial embrace, egg collection, male brood care and raising labyrinth-organ fry.

Overview

Betta splendens is a bubble-nesting labyrinth fish of intermediate breeding difficulty. The male builds and tends a surface bubble nest, and brood care is carried out solely by the male after spawning. Sexual maturity can be reached as early as 4-5 months.

Sexing

Males are more colourful and develop more extended fins than females, an effect exaggerated in ornamental strains. Morphological differences can usually be told around two months after hatching; females possess an ovipositor tube used for egg delivery.

Breeding Setup

• Temperature: warm, within the species range of 24-30 °C
• Cover: the tightest-fitting cover possible to keep the air warm and humid for the fry's labyrinth-organ development
• Nest sites: floating plants plus tubes or canisters under which the male can build
• Water: relatively shallow and still (no strong flow)

Spawning Behavior & Trigger

The male flares, spreads his fins and builds a bubble nest, initially rejecting the female. When ready, the nuptial female pales and dark bars appear on her flanks. Spawning involves the embrace typical of osphronemids, with the male wrapped around the female; around 10-40 eggs are released during each embrace over a session that can last 1-4 hours. The male transfers sinking eggs to the nest as milt fertilises them in the water.

Egg & Fry Care

After spawning the female must be removed, because she will be chased from the male's territory and may otherwise be killed. The male takes sole responsibility for the nest. Eggs hatch in about 24-48 hours, and the fry remain in the nest a further 3-4 days until the yolk sac is absorbed, the male returning any that fall. Once the fry swim freely the male loses interest. First foods are an infusoria-grade food for the first few days, then microworm and Artemia nauplii.

Common Challenges

Males are highly territorial, so pairings must be supervised and the female removed promptly. The labyrinth organ develops at about three to six weeks, so the warm, humid air layer above the water is essential for fry survival.