Nothobranchius Killifish

Also known as: Nothobranchius rachovii

Nothobranchius rachovii is a brightly colored annual killifish native to Mozambique, known for its striking red and blue iridescent patterns in males. The Nothobranchius Killifish originates from Mozambique, specifically in temporary pools and seasonal wetlands in the Sofala Province, reaches 5.5 cm in captivity, typically lives 1.5, and is kept at 22C (72F). Individual fish vary, so treat this as a general guide rather than a guarantee.

Species at a glance

Origin: Mozambique, specifically in temporary pools and seasonal wetlands in the Sofala Province
Adult size: 5.5 cm (2.2 in)
Life span: 1.5
Temperament: Peaceful but males can be territorial toward conspecifics; best kept in species-only tanks or with very calm, similarly sized fish
Tank size: 20 L (5.3 gal)
Water temp: 22C (72F)
pH range: pH 6.0-7.5
Diet: Carnivorous; feeds on live or frozen foods such as brine shrimp, daphnia, bloodworms, and mosquito larvae; will accept high-quality micro pellets but thrives best on live prey
Other names: Nothobranchius rachovii

About the Nothobranchius Killifish

Nothobranchius rachovii is a brightly colored annual killifish native to Mozambique, known for its striking red and blue iridescent patterns in males. It inhabits temporary rain pools that dry up seasonally, leading to a naturally short lifespan. Males display intense coloration to attract females, while females are duller and cryptically colored for camouflage. This species is popular in the aquarium trade for its beauty but requires specialized care due to its annual life cycle.

Lifespan and health

Nothobranchius rachovii is an annual killifish with a naturally short lifespan of 12–18 months in captivity, even under optimal care. This is not a sign of poor husbandry but reflects its evolutionary adaptation to seasonal habitats where adults die after the pool dries, and eggs survive in the mud until the next rainy season. In aquariums, lifespan can be slightly extended by maintaining cooler temperatures (20–22°C / 68–72°F) and providing a varied, protein-rich diet, but exceeding 18 months is rare and often indicates suboptimal conditions for natural breeding behavior. Common health issues include fungal infections (especially on damaged fins or eggs), bacterial ulcers from poor water quality, and internal parasites if live food is not sourced reliably. Swim bladder disorders may occur from overfeeding or sudden temperature shifts. Preventative care includes quarantining new live food, avoiding overstocking, and maintaining stable water parameters. If eggs are desired for breeding, use a peat moss spawning mop and incubate eggs in moist peat at 24–26°C (75–79°F) for 6–8 weeks before rehydrating to hatch fry.

Overview

Care and tank setup

For optimal care, house Nothobranchius rachovii in a minimum 20-liter (5.3-gallon) tank with a soft sandy substrate and dense vegetation such as Java moss or peat fiber to mimic natural spawning grounds. Use a gentle sponge filter to avoid strong currents, and maintain water temperature at a stable 22°C (72°F) with pH between 6.0 and 7.5. Perform 25% water changes weekly using aged, dechlorinated water to prevent nitrate buildup, as these fish are sensitive to poor water quality. Feed small amounts 2–3 times daily with live or frozen foods like newly hatched brine shrimp, daphnia, or microworms; avoid overfeeding as uneaten food quickly degrades water quality. While they can accept crushed flakes or micro pellets, live food is essential for conditioning and spawning success. Lighting should be subdued to reduce stress, and a tight-fitting lid is necessary as they are known jumpers. Tankmates should be chosen carefully: avoid aggressive or fast-moving species. Ideal companions include other peaceful, small killifish like Nothobranchius guentheri or similarly sized, shy fish such as dwarf Corydoras or Otocinclus. Never house multiple males together unless the tank is very large (over 40 liters) with ample hiding spots, as males will fight intensely. Females can be kept in groups of 3–5 per male to reduce harassment.

Adding a Nothobranchius Killifish? Research the species’ adult size and temperament carefully, quarantine new fish before introducing them to your tank, and buy from reputable aquarium stores or breeders.

Breed information on this page is based on the Wikipedia article on the Nothobranchius Killifish, supplemented with additional research. Reviewed for accuracy.