Rasbora is a large genus of small, slender cyprinid fishes native to South and Southeast Asia, part of the broader danio and rasbora group within Cyprinidae. The atlas covers 89 species, from 1–8 in, with records spanning Indonesia, Malaysia, Thailand, Laos, Brunei, Cambodia, India, and Sri Lanka. Most species school in the mid and upper water column of forest streams and floodplain rivers, and a good number are blackwater peat-swamp specialists, living in water stained dark by tannins and low in dissolved minerals.
Rasbora has supplied the aquarium hobby with dependable, easy-to-keep schooling fish for decades. Species such as the blackline rasbora (Rasbora borapetensis), two-spot rasbora (R. elegans), brilliant rasbora (R. einthovenii), and the strikingly patterned clown rasbora (R. kalochroma) are kept in community and biotope aquaria, generally undemanding on water chemistry apart from the true blackwater specialists, which do best in soft, acidic conditions. Diet in the wild and aquarium alike is opportunistic, taking small invertebrates, algae, and detritus.
Most Rasbora species assessed by the IUCN come back Least Concern, reflecting how widespread and adaptable many are, but a minority, largely peat-swamp and small-island endemics in Sumatra, Borneo, and Sri Lanka, are Critically Endangered or Vulnerable as wetland habitat is drained and converted for agriculture. The genus's boundaries have also shifted over time, with several popular aquarium fish once placed in Rasbora now classified in separate genera.