Turquoise Killifish

Nothobranchius furzeri is an annual killifish whose life in the wild fits into a few months. Some lab strains have an average lifespan of only a few months; strains from the wild usually live 6–12 months. Growing and aging in such a short time has made it a favorite model organism for research on aging and embryonic dormancy (diapause).

Males occur in two color forms: red-tailed and yellow-tailed. In both, the head and front of the body are turquoise-blue and the scales have dark red edges. Females are plain gray-brown.

Care in the aquarium is similar to other annual species: a short but intense life, plenty of live food and storing the eggs in damp peat.

It lives in depressions and pools on semi-arid savannas that hold water for only a few weeks or a few months during the rainy season. The water is shallow and murky, and its temperature varies greatly during the day. When the pool dries out the adults die; the eggs wait in the mud for the next rains.

• Volume: 40 liters for one male and two to three females; a species tank is recommended.
• Substrate: Bare bottom; a container filled with boiled peat or fine sand for spawning.
• Water: 22–26°C; neutral to slightly alkaline, moderately hard water. An air-driven sponge filter is enough.
• Lid: A tight lid is essential.
• Maintenance: 30–50% water change weekly; it eats a lot and fouls the water quickly.

Carnivorous, with a very high growth rate. It should be fed two to three times a day with live or frozen foods such as bloodworms, daphnia, mosquito larvae and brine shrimp. Underfeeding juveniles delays both growth and breeding.

Males are active and showy; they fight each other and chase females intensely. Because of its short life and special care routine, it should be kept in a species tank, not with other fish.

Good companions: females of its own species.

Avoid: other Nothobranchius species (hybridization), community fish of any kind, large and active species.

Two to three females per male is ideal. In a small aquarium two males wear each other down. Because of the short lifespan, keepers usually refresh the colony by wetting a new batch of eggs every few months.

It reaches maturity very quickly: well-fed individuals can start spawning at 3–5 weeks. The pair dives into the peat or sand and buries its eggs.

• Collecting: The peat is removed every 1–2 weeks, drained and squeezed until it has the consistency of damp soil.
• Storage: It is kept in a labeled zip-lock bag at 22–26°C in the dark. Because the eggs can pause (diapause) at different stages, they do not all mature at the same time.
• Duration: about 1.5–4 months depending on temperature. Eggs with visible dark eyes are ready for wetting.
• Wetting: The peat is placed in cool, soft, shallow water; the fry hatch within hours. Eggs that do not hatch are dried again.

The fry are fed brine shrimp on the first day. A low water level in the first days reduces the number of fry that fail to fill their swim bladder.

• Aging: Within a few months, fading color, weight loss, a hunched back and slowing down appear; this is not a disease but the natural lifespan of the species.
• Velvet (Oodinium): common; light salting in a species tank is a widespread precaution.
• Dirty water and leftover food quickly lead to losses.

Males are turquoise and red or turquoise and yellow, with broad, colorful fins. Females are smaller, gray-brown and have transparent fins; sexing is easy from a young age.