Annual Killifish Care Guide — Egg Management and Breeding Methods for Nothobranchius and Others

What Are Annual Killifish?

"Annual killifish" (年魚, nengyō) or "killifish" are a special group of tropical fish that inhabit temporary water bodies and seasonal ponds in Africa and South America, where the rainy and dry seasons are clearly defined. While all adult fish die during the dry season when the water dries up, eggs laid in the bottom substrate survive in a dormant state within the dried soil and hatch when the next rainy season arrives—an extraordinary life cycle.

They are called "annual fish" because they complete their entire life cycle within one year. Representative species include Nothobranchius (African species), Fundulopanchax, and Austrolebias (South American species). Many species have extremely vivid body colors, and the coloring of males rivals the beauty of precious gems.

The Appeal and Challenges of Keeping Annual Killifish

Appeal: - Although their lifespan is short (6–18 months), they grow rapidly, allowing you to experience the entire cycle from hatching to spawning in just 3–4 months - You can enjoy a unique spawning process—hatching dormant eggs—that other tropical fish cannot offer - Some species have exceptionally beautiful body coloration with high ornamental value - They are relatively small (5–10 cm) and can be kept in compact aquariums

Challenges: - Their short lifespan means you must continue breeding and managing eggs to pass them to the next generation - Managing dormant eggs (temperature, humidity, storage duration) requires specific knowledge - Many species are sensitive to water quality changes, requiring regular water changes and constant monitoring

How to Set Up a Breeding Tank

Annual killifish can be kept in small 20–30-liter aquariums. The ideal water conditions are slightly acidic to neutral (pH 6.5–7.5), with temperatures between 24–26°C. For the substrate, you can use peat moss on the bottom for spawning, or use a separate spawning box without substrate.

Basic Setup: - Small aquarium (20–30 liters) - Sponge filter (gentle water flow) - Heater (set to 25°C) - Aquatic plants (such as Egeria or hornwort)

Keeping multiple fish together is possible with the same species, but males engage in intense territorial disputes, so one male and 2–3 females in a 45-cm aquarium is ideal.