Killifish
Killifish are a diverse family of small colourful fish from around the world - over 1,250 species.
🗓️ Last reviewed: June 2026
Overview
Killifish are a diverse family of small colourful fish from around the world - over 1,250 species. Some live only a year in seasonal pools (annual killifish); others live several years. Killifish are stunningly coloured, often hard to find in shops, and require species-specific care.
Natural History
Found in freshwater habitats on every continent except Antarctica and Australia. Many live in seasonal pools - eggs survive dry seasons, hatching when water returns. Captive keepers store and ship dried eggs.
Common pet species:
- Golden Wonder Killifish (Aplocheilus lineatus).
- Lyretail Killifish (Aphyosemion australe).
- Clown Killifish (Epiplatys annulatus) - tiny.
- Steel-Blue Killifish (Fundulopanchax gardneri).
- Norman's Lampeye.
- Rachow's Notho (annual).
Appearance
Most 3-10 cm. Brilliant colours and patterns - many of the most striking small fish in fishkeeping.
Temperament & Tankmates
Variable. Males often aggressive toward each other; females and mixed-species in calm community can work. Annual species best in species-specific setups.
Tank Size & Setup
Small species: 40 L (10 gallon). Larger species: 75 L+. Always lidded - killifish jump.
Heavily planted, dim, blackwater conditions for many species.
Water Parameters
Species-specific. Most prefer soft, slightly acidic water.
Diet
Carnivorous. Frozen and live foods preferred - daphnia, bloodworms, baby brine shrimp, micro worms.
Health & Lifespan
Annual species: 1 year. Non-annual: 2-5 years.
Pros & Cons
Pros: brilliant colours, niche hobby with active community, fascinating biology. Cons: harder to find than community fish, species-specific care, short lifespans.
Killifish - frequently asked questions
Why "killifish"?
From Dutch "kil" meaning small stream - not from "killer." They are mostly peaceful.
Annual vs non-annual?
Annual species evolved to complete their lifecycle in seasonal pools - eggs diapause through dry seasons. Captive keepers cycle generations through stored eggs.
Where do I get them?
Specialist online breeders, killifish clubs (American Killifish Association is active). Rarely in pet shops.
How long do they live?
1 year for annuals; 2-5 years for non-annuals.
Beginner fish?
Not typically - niche hobby with species-specific needs.
🧠 Test yourself: guess the fish
Three clues from our quiz bank, each about another of our fish. Can you name them?
Clue 1.This stout algae-eating catfish has bony armor plates and males that grow fleshy tentacle-like growths on the snout.
It's the Bristlenose Pleco - read the full profile →
Clue 2.This tiny schooling fish glows with an iridescent blue stripe and a red streak along its rear half.
It's the Neon Tetra - read the full profile →
Clue 3.This peaceful armored aquarium fish gulps air from the surface and breathes part of it through its gut.
It's the Corydoras Catfish - read the full profile →