Breeding Celestial Pearl Danio
How to breed Danio margaritatus, an egg-scattering nano fish: sexing, conditioning, spawning medium, egg numbers, hatch time and rearing the fry.
Overview
Danio margaritatus is an egg-scattering spawner that shows no parental care, and Seriously Fish notes the adults eat the eggs, so they must be removed immediately after spawning. In good condition the fish spawn frequently; Wikipedia reports they spawn almost every day in nature, with females needing recovery time between batches.
Sexing
Males have a steel-to-deep blue body with intense red and black striping in the fins, pearly-white spots, and a reddish abdomen when spawning. Females are blue-green with weaker fin color, cream-golden spots, and a larger, rounder body; a small dark vent (anal) marking appears when they are ready to spawn.
Conditioning the Breeders
Well-conditioned fish spawn readily. Pairs or groups can be conditioned in the main tank or in small separate containers of 10-15 litres.
Breeding Setup
- Fine wool mops, Taxiphyllum or other fine-leaved plants as the spawning medium
- Aged water; a small air-powered sponge filter is optional
- Strong lighting and filtration are not required
Spawning Behavior & Trigger
Males display to passing females and conduct brief chases before pairs move into the vegetation to deposit eggs. Around 30 mildly adhesive eggs are deposited in a typical spawning event. Wikipedia adds that rival males may follow a mating pair to fertilize or eat the eggs.
Egg & Fry Care
Remove the adults after spawning. Incubation is temperature-dependent at roughly 72 hours, and Wikipedia gives 3-4 days at 24-25 C for larvae to emerge; fry are free-swimming 3-4 days post-hatch. First foods are Paramecium or a 5-50 micron proprietary dry food, progressing to Artemia nauplii and microworm. Coloration develops from about week 12.
Common Challenges
Egg predation by the adults and other males is the main risk, so a separate spawning medium and prompt removal of adults are important. The tiny fry require infusoria-grade first foods.