Korthaus Killifish

Korthaus Killifish

Korthaus Killifish (Nothobranchius korthausae) is a small, vividly colored annual killifish from Mafia Island, off the coast of Tanzania. Males have blue-green scales outlined in red, with bold red markings through the fins and tail. Two color forms are kept in the hobby — a red form, now the more popular, and the original yellow form, with intermediate fish in between. Females are plain brownish-gray in both forms. The species was described in 1973 and named for Edith Korthaus, who collected the first fish. It is known from only a few sites in the wild, and all aquarium fish are captive-bred.

⚠ Annual Killifish — Short Lifespan Is Normal: In the wild, Nothobranchius live in seasonal pools that dry up every year. The adults die, and the next generation survives as eggs buried in the mud. In the aquarium, Korthaus Killifish typically live about a year. When an adult dies at that age, it is normal biology, not a sign that something went wrong. If you want to keep the line going, collect eggs while your fish are in their prime.

Korthaus Killifish are one of the easiest Nothobranchius to keep, which makes them an ideal first annual killifish. They are peaceful and can be kept as a pair, a trio of one male with two or three females, or a small group with extra females. Males display to each other with spread fins, but rarely do real damage. They do best in soft, slightly acidic to neutral water at moderate temperatures, in a tank with gentle filtration, some floating plants, and a dark substrate that brings out the male colors.

Keep only one Nothobranchius species per tank. All species in the genus will readily interbreed, and the hybrids are less attractive and less valuable than pure-strain fish. Most keepers also keep the red and yellow forms apart, so each strain stays true.

Feeding & Care Tip: Killifish are carnivores, and frozen and live foods bring out the best color and spawning condition. Hikari Frozen or Freeze-Dried Bloodworms and Hikari Frozen or Freeze-Dried Baby Brine Shrimp make the best staples, with Hikari Frozen Daphnia for variety. Many will learn to take Hikari Micro Pellets once settled. Feed small amounts 2–3 times daily — steady feeding matters for a fish that grows and matures this quickly.

Breeding is straightforward. Give the fish a container of peat moss, and the pair will dive into it to lay eggs. Remove the peat every week or two, squeeze out the excess water, and store it slightly damp in a sealed bag at room temperature. After about 6–8 weeks, the eggs show developed eyes and can be hatched by adding soft water. Unlike most Nothobranchius, some Korthaus eggs will even hatch without a dry period. The fry are free-swimming right away and can take baby brine shrimp or microworms from the first day.

Care & Ideal Parameters