Aquarist Atlas
Aquarist Atlas · the danionin cyprinids

Danios & Rasboras

Danios and rasboras are the quick, glittering, schooling cyprinids of tropical Asia — the small fishes that fill the upper water of monsoon streams, forest pools and rice paddies from the Western Ghats east to Borneo. The aquarium core is famous: the indestructible zebra danio (Danio rerio), the deep-bodied giant danios (Devario), the jewel-like celestial pearl danio (Danio margaritatus), the near-invisible transparent Danionella — among the smallest vertebrates on Earth — and, on the rasbora side, the harlequin (Trigonostigma) and the tiny chili rasboras (Boraras). They are one subfamily, the Danioninae, and the line between “danio” and “rasbora” is genuinely blurred — several fish sold as rasboras are really danios. 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

“Danio” and “rasbora” are hobby groupings, not separate lineages — they are the same subfamily, the Danioninae, and the boundary between them is fuzzy. The celestial pearl danio spent years in the trade as the “galaxy rasbora,” and the green neon “rasbora” is really Microdevario kubotai, a danio. We follow the Catalog of Fishes for valid names, so a fish you know under one label may appear here under its current genus, with the trade name noted. We keep the two together and leave out the true barbs, the loaches, Garra and the algae-eater “sharks,” which are their own groupings. Nearly all of these fish breed the same way: they are egg-scattering, non-guarding spawners that release adhesive eggs over plants or gravel and tend neither eggs nor fry — the harlequin rasbora, which sticks its eggs under a leaf, is the notable exception. You will not find bubble-nests or mouthbrooding here.

A shoal of zebra danios, each striped horizontally in blue and gold, swimming together near the surface
The zebra danio (Danio rerio) is among the hardiest of fish and the most-studied vertebrate in the lab — kept in a group it is constantly active near the surface, and it spawns at the first warm rain, scattering eggs and eating any it can catch.
A male celestial pearl danio, deep blue spangled with pearl spots and edged in red-orange fins
The celestial pearl danio (Danio margaritatus) — long sold as the “galaxy rasbora” before science placed it in Danio — is the misnamed-fish problem in one animal, and a reminder that danios and rasboras are a single, tangled lineage.
A group of harlequin rasboras, copper-pink with a black wedge on the rear flank, among fine plants
The harlequin rasbora (Trigonostigma heteromorpha) lays its eggs on the underside of a broad leaf rather than scattering them — the one real departure from the family’s egg-scattering norm, and proof that “rasbora” covers more than one habit.

Photos © Adobe Stock

233 species in the atlas

We treat the danios and rasboras as one section — the schooling danionin cyprinids of tropical Asia — grouped here by a friendly size-and-kind axis (true danios, giant danios, micro danios, the transparent Danionella, the flying barbs, and the rasboras and dwarf rasboras) rather than by raw genus. The true barbs, loaches, Garra and algae-eater “sharks” are deliberately left out. Following the Catalog of Fishes and FishBase, the valid set is large and still being written up; new accounts are added as they are researched.

Species

233 of 233 species

True danios · 45

The classic schooling danios — the zebra and pearl danios (Danio, Brachydanio), the celestial pearl danio, and the keel-bellied hatchet danios (Chela, Laubuka). Quick, active, surface-loving fishes of the streams and paddies of India, Myanmar and Indochina; the heart of the danio side of the trade.

Giant danios · 48

The larger, deeper-bodied danios (Devario and allies) — the giant danio and its kin, robust schoolers of fast, well-oxygenated hill streams and rivers from the Western Ghats across mainland Asia. Tougher and bigger than the true danios, and built for current.

Micro danios · 18

The truly tiny danios (Microdevario, Sundadanio, Microrasbora, Horadandia) — nano fishes under a few centimetres, including the green neon 'rasbora' (a Microdevario) and the blue neon (Sundadanio) of Sundaland's blackwater peat swamps. Small, jewel-coloured, and easily overlooked.

Transparent danios · 5

Danionella — see-through fishes of leaf-litter forest streams in Myanmar, among the smallest of all vertebrates. Recently famous in science: the males of some species produce sound louder than a jet engine relative to their size, and their transparent brains make them a living window for neuroscience.

Flying barbs · 8

Esomus — the flying barbs, slim surface fishes with very long barbels, of still and slow waters across South and Southeast Asia. Despite the name they are danionins, not true barbs; they hang at the surface and can skip across it to escape predators.

Rasboras · 102

The rasboras proper (Rasbora and kin — Trigonostigma, Trigonopoma, Brevibora, Kottelatia, Rasboroides) — the schooling rasboras of Southeast Asian streams, blackwaters and rice paddies, from the harlequin to the scissortail. Mostly egg-scatterers; the harlequins glue their eggs under broad leaves.

Dwarf rasboras · 7

The nano rasboras (Boraras, Sawbwa) — the chili and dwarf rasboras, among the smallest aquarium fish, of tannin-stained peat-swamp and slow forest waters in Sundaland and Myanmar. Intensely coloured, shy, and best kept in large groups in soft, gentle water.

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