Fish
Blue Killifish
Aphyosemion coeleste
Origin: Native to forest streams and small pools of Central Africa, mainly Gabon and the Republic of Congo. Found in slow-moving or stagnant waters with leaf litter and dense marginal vegetation that produce soft, acidic conditions.
Also known as: Coeleste killifish, Sky-blue aphyosemion
Fact sheet
- Size
- 6 cm
- Lifespan
- 3 years
- Minimum tank size
- 40 L
- Temperature
- 20–24 °C
- pH
- 6–7
- Hardness GH
- 2–8 °dH
- Temperament
- Peaceful
- Social behavior
- Harem
- Swimming zone
- Middle, Top
- Diet
- Carnivore
- Jumps out
- Yes
- Eats plants
- No
Overview
The Blue Killifish is a small member of the family Nothobranchiidae, prized for the striking coloration of males. Males display rich blue and turquoise tones overlaid with red and orange spots across the body and fins; females are drab brownish-gray. Unlike many killifish, Aphyosemion coeleste is non-annual — it does not depend on seasonal pool drying and can live several years. Active in the middle and upper water column, it thrives as pairs or small harems. Best suited to dedicated nano tanks with soft water. Stable water parameters and regular maintenance are essential.
Appearance
Males reach 5–6 cm; the body is elongated and slightly compressed. Coloration is intense blue-turquoise, overlaid with red-orange spots on the flanks and colorfully edged fins with contrasting borders. Females are smaller and plainer — brownish-gray with rounded, unpatterned fins.
Care
A 40-liter tank with a tight-fitting lid is needed — these fish jump readily. Soft, slightly acidic water: pH 6.0–7.0, GH 2–8, temperature 20–24 °C. Avoid bright lighting; dark substrate, floating plants, and Indian almond leaves improve comfort. Gentle filtration without strong current. Weekly 20–25% water changes.
Feeding
Prefers live and frozen foods: bloodworms, brine shrimp, daphnia, tubifex. Accepts quality dry killifish granules. Feed twice daily in small portions. A varied diet intensifies male coloration and encourages spawning.
Compatibility
Peaceful overall; males may compete with each other. Best kept as one male with 2–3 females. Compatible with small peaceful fish sharing similar water parameters. Avoid large or aggressive tank mates.
Breeding
Plant-spawner: eggs are deposited on fine-leaved plants or roots. A separate breeding tank is recommended. Incubation takes 2–3 weeks at 22–24 °C. Fry are tiny; first foods are infusoria and brine shrimp nauplii. Remove breeders after spawning.
Fun facts
The species name coeleste is Latin for 'heavenly,' referencing the sky-blue males. Non-annual, it lives up to 3–4 years in captivity without requiring substrate drying. Under stress, the fish releases chemical alarm cues that warn conspecifics of danger.