Bluefin Notho (Nothobranchius rachovii)

Nothobranchius rachovii, the Bluefin Notho or Rachow's Nothobranchius, is widely regarded as the most spectacularly coloured freshwater fish in the world. Male specimens in prime condition display a jaw-dropping pattern of red and orange bands on the body, brilliant blue-green iridescence on the head, and a caudal fin banded in vivid orange and electric blue with a dark margin — a colour combination that surpasses virtually every other freshwater fish for sheer brilliance.

Native to the coastal lowlands of Mozambique and southern Tanzania, Nothobranchius rachovii inhabits temporary seasonal pools and floodplain areas that fill with each rainy season and dry out completely during the dry season. As an annual killifish, individual fish live for only 6–12 months, dying when the pools dry up. Their eggs, however, are deposited in the substrate and survive desiccation in a state of diapause — hatching when rains return.

In captivity, breeding the Bluefin Notho requires collecting eggs from peat substrate, drying and storing the peat in a sealed bag for 6–12 weeks (simulating the dry season), then 'hatching' the eggs by adding soft, slightly warm water. This process is part of the fascination of keeping annual killifish.

Despite the short lifespan, Nothobranchius rachovii are among the most rewarding and spectacular fish in the hobby. A single male in a species tank is a living jewel.

Tank Setup: A 20–30 litre species tank for a pair or trio. Fine peat substrate 3–5 cm deep for spawning. Dense floating plants for cover. Gentle sponge filtration. A lid is essential — killifish jump readily. No other fish — males will fight and even females compete for food.

Water Parameters: Temperature 22–26°C; pH 6.0–7.0; GH 2–8 °dH; KH 1–4 °dH. Soft, slightly acidic water preferred. Avoid hard, alkaline conditions.

Feeding: Carnivore. Feed live and frozen foods exclusively or primarily: live Daphnia, bloodworm, brine shrimp, Tubifex, micro worms. Dry foods may be accepted by some individuals. Feed once to twice daily. Excellent appetite — feed generously to fuel their fast metabolism and short life.

Tank Mates: Best kept as a species-only tank. Males fight each other. Can keep one male with two to three females, or females only in a group. Never mix with aggressive species or those that will outcompete them for food.

Behaviour: Males display elaborately and constantly to females. Spawning is frequent — females lay a few eggs daily in the peat substrate. Collect and store eggs monthly for incubation. Short-lived but intensely active and colourful.

Health: Hardy for their lifespan. The main challenge is maintaining appropriate annual cycle conditions (diapause eggs). Individual fish are susceptible to velvet and ich — address immediately as their short lifespan leaves little recovery time. Excellent water quality essential.