Redtail notho (Nothobranchius guentheri) care guide

Group

Freshwater fish

Other names

Redtail notho, Redtail nothobranch, Gunther's nothobranch

Family

Nothobranchiidae (African killifishes)

Origin

Endemic to Unguja, the main island of Zanzibar, Tanzania: seasonal coastal pools, swamps and ditches that dry out completely in the dry season.

Water

freshwater

Maximum size

4.1 cm

Temperature

22–25°C

pH

6.5–8

Hardness

Soft to medium, 4–10 dGH (FishBase)

Minimum tank

41 litres

Care level

beginner

Temperament

semi_aggressive

Care

One of the easier Nothobranchius and often suggested as a first annual killifish. Like all annuals it is short-lived, so it is kept going from stored eggs rather than as long-lived adults. Keep one male with two or three females in a species tank: males are aggressive towards each other and give a lone female a hard time. A tank with a base of about 45 × 30 cm (around 41 litres) suits one male and two or three females. Use a peat or soft, dark substrate, some plants or floating cover for the females, and gentle filtration. A tight-fitting lid is essential – this species is a known jumper. Keep it at 22–25 °C. Seriously Fish gives pH 6.5–8.0; wild pools are warm, slightly alkaline and often cloudy. FishBase gives a hardness of 4–10 dH. Do regular partial water changes. Males are blue-green with two or three slanting red bars on the gill cover and a red tail edged in black; females are smaller, plain yellowish brown. It can be confused with N. melanospilus, which lives in the same area; Costa (2017) redescribed the species to clear up the mix-up. Old books may list it as Fundulus, Adiniops or Aphyosemion guentheri. The IUCN lists it as Endangered: it lives only in a small part of Unguja, where its pools are being lost to farming. Fish in the trade are hobby-bred, so buy from breeders who keep their lines properly labelled and separate. Sources: Seriously Fish (seriouslyfish.com/species/nothobranchius-guentheri/); FishBase (fishbase.se/summary/Nothobranchius-guentheri.html); Wikipedia (en.wikipedia.org/wiki/Nothobranchiusguentheri). Checked October 2026.

Diet

A micropredator. Offer small live or frozen foods such as Daphnia, brine shrimp (Artemia) and bloodworm. Most will take dried food only now and then, so live and frozen foods should be the main diet.

Breeding

An annual peat spawner. Condition the sexes apart on live and frozen food, then put one male with two females at pH 7.0–7.5 and 23–25 °C with a layer of peat; they will spawn daily for about a week, the pair pushing into the peat and laying one egg at a time. Squeeze the peat until damp (not wet) and store at 21–24 °C for 8–14 weeks (FishBase says 3–4 months). Wet it in shallow water to hatch; eggs wetted too early give weak fry. Some eggs develop slowly, so drying the peat again and rewetting weeks later often brings a second hatch. Feed infusoria first, then brine shrimp nauplii or microworm after about two days, and bigger foods after two weeks. Raise the water level gradually and change water often; the fry are prone to velvet. FishBase says they mature in 6–8 weeks.

Compatibility and tank mates

Best in a species-only tank. Keep one male per tank unless there is room for several territories, with two or three females per male to spread his attention. Do not keep with other Nothobranchius, as the plain females are easily mixed up.

Last updated 4 October 2026. Community-edited care guide on Aquatic-Auctions.