Annual Killifish Peat Spawning Guide: Nothobranchius Eggs

Few fish tell a stranger life story than the African annual killifish. In the seasonal pools of Mozambique and Tanzania, fish such as Nothobranchius rachovii and Nothobranchius guentheri hatch, colour up, spawn and die inside a single rainy season, with their eggs surviving the dry months buried in mud. This annual killifish peat spawning guide from Gensou Aquascaping at 5 Everton Park walks Singapore hobbyists through the spawning box, the incubation period, and the moment of rehydration. Get the substrate moisture right and you can hold viable eggs for months on a shelf.

Quick Facts

• Peat substrate: fine milled sphagnum, boiled and cooled, squeezed to a damp clump
• Spawning box: 10-15 cm plastic container, 2-3 cm peat depth, placed in breeding tank
• Incubation: 8-12 weeks for most Nothobranchius, up to 4 months for drier-climate species
• Storage temperature: 22-26 degC in a sealed zip bag, away from direct sunlight
• Rehydration water: cool (18-22 degC), soft, oxygen-rich, 3-5 cm deep
• Fry accept newly hatched brine shrimp within 12 hours of wetting
• Adult lifespan: 8-14 months in captivity; spawn from 6-8 weeks of age

Why Peat Spawning Mimics the Wild

Annual killifish evolved in temporary pools that dry out for six to nine months each year. Eggs sit in the damp mud through diapause, a true developmental pause, until the next monsoon refills the depression. Recreating that on your shelf in a Singapore flat means a peat layer that stays damp but never wet, and an incubation spell in a warm cupboard. The eggs continue developing slowly even while stored, so timing the rehydration is a decision based on embryo eye-spots, not a calendar.

Preparing the Peat

Use milled sphagnum peat moss, the sort sold for orchids at garden shops along Thomson Road. Boil it for 10 minutes to kill hydra, planaria eggs and fungal spores, then drain through a fine sieve. Squeeze handfuls until no water drips but the clump still feels cool and heavy. If water runs out when you press hard, it is too wet and the eggs will fungus; if it crumbles dry, embryos desiccate. A useful reference point is damp coffee grounds.

Setting Up the Spawning Box

A shallow plastic tub, roughly 12 by 8 cm and 4 cm deep, works for a pair or trio. Fill it with 2-3 cm of prepared peat and lower it slowly into the breeding tank so the peat wets from below without clouding. Keep water level just above the rim for a day, then drop it to the rim height. A mated pair will dive into the peat nose-first, the male clamping the female briefly as eggs are pressed into the substrate.

Collecting and Drying Eggs

After one to two weeks, lift the box out. Tip the peat into a sieve, rinse briefly with tank water to remove fry food residue, then squeeze firmly and spread the damp peat on newspaper for 20 minutes. You want it slightly drier than when it went in. Bag it in a labelled zip-lock with species, date and parent line. Pea-sized amber eggs become visible against the dark peat under a 10x loupe.

Incubation Times by Species

Not all annuals run on the same clock. Nothobranchius guentheri and N. eggersi hatch after 8-10 weeks. N. rachovii sits longer at 10-14 weeks. N. furzeri, famous as a vertebrate ageing model, can be ready in 6 weeks if kept warm. South American Austrolebias and Simpsonichthys lean longer, often 16 weeks. Check weekly under a strong torch; when eye-spots and a dark body outline appear inside the egg shell, hatching is imminent.

Rehydration Technique

Tip the peat into a shallow container and flood with cool, soft water at 18-22 degC. The temperature shock triggers hatching within hours. Add a pinch of dry yeast to consume oxygen briefly, which also seems to stimulate stragglers. Fry swim horizontally within a day and should be fed newly hatched brine shrimp immediately. Any unhatched eggs can be re-dried and stored for another round, often called the second wetting, six to eight weeks later.

Belly-Sliders and Common Failures

Belly-sliders are fry that hatch with underdeveloped swim bladders and lie on the bottom. Causes include peat that was too wet during storage, insufficient oxygen at hatching, or incubation at too high a temperature. Keep storage around 24 degC, not warmer. Hatch into water no deeper than 3 cm for the first 48 hours so fry can reach the surface without effort. Discard peat showing white fungal fluff; it means moisture crept too high.

Singapore Keeper Notes

Local ambient temperatures of 28-31 degC are too warm for egg storage long term. A wine cabinet set to 22 degC, a cupboard under air-conditioning, or the vegetable drawer of a spare fridge all work. PUB tap water with a DI or peat filter pass makes acceptable rehydration water after dechlorination; aim for conductivity under 200 microsiemens. Fellow killie keepers on local Facebook groups often swap eggs by post, which is how many Singapore collections of N. rachovii Beira and N. eggersi originated.

Bringing Up the Fry

Growth is rapid. Fry double in size each week on a diet of brine shrimp nauplii, microworms and later chopped blackworm. Males colour by week four and spawn by week six to eight. Keep sexes separated once sexually mature to rest females, rotating a male in every few days. Annuals burn bright and burn fast; a well-fed pair produces hundreds of eggs across a three-month spawning window.

Related Reading

• Clown Killifish Breeding Guide
• Golden Wonder Killifish Breeding Guide
• How to Breed Aphyosemion Killifish
• Norman’s Lampeye Killifish Breeding Guide
• Blue Gularis Killifish Care Guide