Aquarist Atlas
Aquarist Atlas · the egg-laying toothcarps

Killifish

Killifish are the egg-laying toothcarps — the half of the Cyprinodontiformes that does not bear live young (those, the guppies and their kin, have their own Livebearers section). It is one of the most widely spread of all freshwater groups, on every warm continent: the African annual Nothobranchius of seasonal savanna pools and the jewel-coloured Aphyosemion of the rainforest, the pike-shaped Aplocheilus and Epiplatys panchax of Asia and Africa, the South American annual killies and the rivulines that walk between pools, the self-fertilizing mangrove rivulus, the desert Cyprinodon pupfish, the American flagfish and topminnows, and the Mediterranean Aphanius. This section is built to the same standard as the cichlid, cory and pleco pages: researched, cited accounts with no Wikipedia and no invented facts.

© Adobe Stock

The axis that organises the killies is how and where they spawn, and it splits the group in two. The annual killies — the African Nothobranchius and the South American Austrolebias, Hypsolebias and their kin — live in pools that dry out every year; they race through a life cycle in weeks and leave drought-resistant eggs buried in the mud, which wait out the dry season in a suspended diapause and hatch with the next rains. The non-annual killies — most Aphyosemion, the panchax, the rivulines, the pupfish, the flagfish and Aphanius — spawn in permanent water, hanging their eggs on plants or spawning mops over days or weeks. And one lineage stands apart: the mangrove rivulus Kryptolebias, the only vertebrate that routinely fertilizes its own eggs internally. Each species' page records which mode it uses, alongside its water chemistry.

A male Nothobranchius killifish in red and gold, the white-edged fins of a savanna annual
The annual killies are the sprinters of the fish world — males flare in metallic blue, red and gold, and a wild fish may live only a few months between one rainy season and the next, its eggs the only part that bridges the drought.
A West African killifish with a red-netted body and a lyre-shaped tail among fine plants
The non-annual rainforest killies hang their eggs in fine-leaved plants and live for years in cool, shaded forest streams — quieter, longer-lived fish than their annual cousins, and the heart of the West African killifish hobby.
A deep-bodied pupfish over pale sand, its flanks scattered with iridescent green spots
The pupfish and flagfishes are the toughest of the family — deep-bodied generalists of warm, shallow, often salty water. Several desert-spring pupfish survive in a single pool, which makes them among the most endangered animals on Earth.

Photos © Adobe Stock

861 species in the atlas

That spans the egg-laying Cyprinodontiformes following the Catalog of Fishes and FishBase — the Nothobranchiidae, Aplocheilidae and Rivulidae of the “true” killies, plus the egg-laying Fundulidae, Cyprinodontidae, Aphaniidae, Valenciidae, Profundulidae and the lampeye Procatopodidae — grouped here by a friendly region-and-lifestyle group rather than by raw genus. Killifish include some of the most threatened freshwater fish alive: desert-spring pupfish, Mediterranean Aphanius and Valencia, and single-pool annual killies. New accounts are added as those species are written up.

Species

861 of 861 species

African annual killies · 109

Nothobranchius and their annual kin (Pronothobranchius, Fundulosoma, the West African Callopanchax) — the seasonal-pool killies of the African savanna. Their eggs survive the dry season buried in the mud; the fish hatch, mature and spawn within weeks. Among the most colourful and shortest-lived of all vertebrates.

African killies · 142

Aphyosemion, Fundulopanchax and their non-annual West and Central African allies (Chromaphyosemion, Scriptaphyosemion, Nimbapanchax, Archiaphyosemion, Episemion, Fenerbahce). Forest-stream and swamp egg-layers — most are plant-spawners, though Fundulopanchax and a few others bury eggs in soft substrate as a 'semi-annual' hedge against a falling water table.

Panchax · 53

The panchax — Epiplatys of Africa, Aplocheilus of South and Southeast Asia, and the Malagasy Pachypanchax. Surface-oriented, pike-shaped plant-spawners of still and slow waters; the clown killi (Epiplatys annulatus) and the golden wonder (Aplocheilus lineatus) are hobby mainstays.

Lampeyes · 79

The lampeyes — the small, iridescent-eyed Procatopodidae of Africa (Poropanchax, Aplocheilichthys, Lacustricola, Micropanchax, Procatopus, Plataplochilus, Hypsopanchax) and the Lake Tanganyika Lamprichthys. Schooling egg-layers of clear streams, swamps and rift lakes, named for the glowing blue-green patch above the eye; non-annual plant- and crevice-spawners.

South American annual killies · 207

The Neotropical annuals — Austrolebias, Hypsolebias, Cynolebias, Simpsonichthys, Nematolebias, Pterolebias, Rachovia, Austrofundulus and kin. Like the African Nothobranchius they live a single wet season in temporary pools, leaving drought-resistant eggs in the mud. Many are single-pool endemics under acute threat.

South American rivulines · 124

The non-annual rivulines — Anablepsoides, Laimosemion, Atlantirivulus, Cynodonichthys, Melanorivulus and Rivulus. Hardy plant-spawners of permanent forest streams and pools across the Amazon, the Guianas and the Atlantic Forest; several leave the water and skip overland between pools.

Mangrove rivulus · 7

Kryptolebias — the mangrove rivulus and its relatives, of brackish coastal mangrove from Florida to Brazil. Kryptolebias marmoratus and K. hermaphroditus are self-fertilizing hermaphrodites — the only vertebrates known to reproduce by routine internal selfing — and survive weeks out of water in damp logs and crab burrows.

Pupfish · 55

Cyprinodon and its kin (Megupsilon, Cualac, Floridichthys) — the pupfish of North and Central American deserts, springs and coasts. Tough generalists that tolerate heat and salinity lethal to most fish; the desert-spring endemics, above all Devils Hole's Cyprinodon diabolis, are among the rarest animals on Earth.

American killifish · 52

The North and Central American egg-layers outside the pupfish — Fundulus and Lucania (the topminnows and killifish of the Atlantic and Gulf coasts), the American flagfish Jordanella floridae, the Central American Profundulus and Tlaloc, and the spring-dwelling Crenichthys and Empetrichthys of the Great Basin.

Mediterranean & Asian killies · 33

The Old-World toothcarps of the arid belt — Aphanius and its split genera (Aphaniops, Paraphanius, Esmaeilius) around the Mediterranean and east to Iran and Pakistan, and the European Valencia. Relicts of saline springs, coastal lagoons and desert wadis, many are Critically Endangered as their waters are drained or invaded.

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