Aquarist Atlas
Aquarist Atlas · live-bearing fishes

Livebearers

The livebearers are the fishes that give birth to free-swimming young instead of scattering eggs. The familiar ones — the guppy, molly, platy and swordtail of the family Poeciliidae (Poecilia, Xiphophorus) — are among the most-kept aquarium fishes on earth, prized for their colour, their hardiness, and the ease with which they breed. Around them sits a much wider radiation: the highland-Mexican splitfins (Goodeidae), many of them clinging to existence in a single spring or river; the surface-cruising four-eyed fishes (Anablepidae); and the live-bearing halfbeaks of Southeast Asia (Zenarchopteridae). This section is an atlas of those families built to the same standard as the cichlid, cory, and pleco pages: researched, cited species accounts with no Wikipedia and no invented facts. It will grow species by species.

© Adobe Stock

Many livebearers are kept and traded by wild locality or strain rather than by species alone: a guppy population from a particular Venezuelan river, an “Endler” line, or a splitfin from one named Mexican spring can differ sharply from the fish next door in colour, size, or behaviour — and, for the threatened goodeids, a locality is often the unit that conservation breeding works to preserve. Where a species or population carries such a label, it is shown on that species' page.

382 species in the atlas

The livebearer families span the Americas and Southeast Asia, from the ubiquitous guppy to splitfins surviving in a single spring. This atlas grows toward that diversity species by species, as accounts are researched and cited.

A mottled, black-spotted livebearer with an orange belly over a planted aquarium bed
Endlessly variable colour — a century of line-breeding atop wild diversity, all on fish that give birth to live young.
A pair of peppered wild-type livebearers with orange-edged tails
Wild-type forms are subtle: peppered flanks and a flash of fin colour, a world away from the fancy strains they seeded.
A single livebearer with blue-green structural iridescence and an orange fin edge
Structural blue-green shimmer over a pale belly — and, in males, the gonopodium: an anal fin reshaped for internal fertilisation.

Photos © Adobe Stock

Species

382 of 382 species

Poeciliidae · 275

The classic live-bearing toothcarps — guppies, mollies, platies, swordtails (Poecilia, Xiphophorus) and their many wild relatives across the Americas.

Goodeidae · 45

The splitfins (Goodeinae) — a live-bearing radiation endemic to the Mexican highlands, many critically threatened; plus the North American Empetrichthyinae.

Anablepidae · 19

The four-eyed fishes and one-sided livebearers (Anableps, Jenynsia) — surface-dwelling New World livebearers of fresh and brackish water.

Zenarchopteridae · 43

The viviparous halfbeaks (Nomorhamphus, Dermogenys) — live-bearing surface predators of Southeast Asian streams and estuaries.

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