Eggers' Nothobranchius (Nothobranchius eggersi) Breeding Guide

Breeding the Tanzanian annual killifish Nothobranchius eggersi: peat spawning, drying eggs to tobacco consistency through diapause, and rewetting to hatch.

Overview

Nothobranchius eggersi is an annual killifish from Tanzania, known from many local strains across the country including the Rufiji and Ruhoi river areas. In the wild it occupies shallow temporary pools and swamps with a muddy or leaf-litter bottom that dry out seasonally. It is best kept in a species-only tank in soft, slightly acidic water at about 23-25 °C.

Sexing

Males have rich red flanks and powdery blue scales, while females are smaller and plain. A typical breeding group is one male with three to four females, matching its natural harem structure.

Conditioning

The species fares best on small live foods such as daphnia and small bloodworm, though it often accepts frozen and sometimes dried foods. Generous feeding of well-fed adults can yield up to about 100 eggs per spawning period.

Breeding Setup

Provide a species tank with peat as a substrate, or place a container of peat at the bottom for egg deposition. The fish are bottom spawners that deposit eggs into the medium. Soft acidic water and subdued light keep the pair productive.

Spawning Behavior & Trigger

During each spawning embrace the adults release a small batch of eggs into the peat. The egg-laden peat is then collected and dried down to a damp, pipe-tobacco-like consistency for storage.

Egg Diapause & Hatching

The damp peat is stored for several weeks at roughly 26-28 °C (about 79-82 °F). In the wild the buried eggs remain dormant in diapause for 8 to 12 weeks and hatch when rains refill the pool. To reproduce this, gradually rehydrate the peat moss as if a wet season has arrived; the embryos sense the environmental change and begin to hatch, a process that can take several weeks. Use soft, cool water for the wetting.

Common Challenges

Storing the peat too wet or too dry, or wetting before diapause is complete, reduces hatch rates. As with other annuals, eggs that fail to hatch on the first wetting can often be re-dried and wetted again after a further rest.