Argentine Pearlfish (Austrolebias bellottii) Breeding Guide

Breeding the cool-water Argentine annual killifish Austrolebias bellottii (formerly Cynolebias bellottii): peat spawning, dry diapause and rewetting to hatch.

Overview

Austrolebias bellottii is an Argentine annual killifish first described as Cynolebias bellottii by Steindachner in 1881 from La Plata, Argentina, and is the type species of the genus Austrolebias. It occurs in the basins of the Paraná and Uruguay rivers in Argentina and Uruguay, in temporary pools that dry seasonally. Like other South American annuals it is a cool-water species whose eggs survive the dry season in the substrate.

Sexing

Males are deep blue with vertical pale bars across the flanks, while females are smaller, plainer and brownish. A single male is housed with several females in cool water.

Conditioning

As a carnivore it should be conditioned on small live and frozen foods such as daphnia, bloodworm and brine shrimp. As a cool-water annual it does best below tropical temperatures, in soft, slightly acidic water.

Breeding Setup

Provide a small tank with a deep peat substrate for the fish to bury eggs in, with cover for the female. The fish dive into the peat to spawn. Soft acidic water and cool temperatures match its natural pools.

Spawning Behavior & Trigger

The pair dives into the deep peat and lays eggs within the medium. After spawning the peat is collected, partially dried to a damp consistency and stored, since later rehydration triggers hatching. The egg-laden peat is kept in a dark, cool place.

Egg Diapause & Hatching

Following the South American annual pattern, the damp peat is stored for several months while the embryos develop and may rest in diapause; the period can be shortened or extended by varying the storage temperature. Flooding the peat with soft, cool water then triggers hatching, and the fry are large enough to take baby brine shrimp at once.

Common Challenges

Keeping or storing the fish too warm shortens life and harms egg viability. Cool, dark storage and a second drying-and-wetting cycle for eggs that fail to hatch on the first flooding give the best yields.