Pethia is a genus of small barbs in the carp family Cyprinidae, split off from the old catch-all genus Puntius in a 2012 taxonomic revision that untangled South Asia's barb diversity. The atlas covers 44 species, almost all genuinely small — from 1 in up to a 5.5 in outlier — with the compact, deep-bodied shape and often strongly patterned flanks typical of the group. They are stream and pond fish of South and Southeast Asia, with atlas records from India, Myanmar, Sri Lanka, Bangladesh, Nepal, Pakistan, Thailand, and Afghanistan, generally favouring shaded, slow-to-moderate flowing water in forest streams and rice-growing lowlands.
Pethia supplies some of the aquarium hobby's most familiar barbs: the rosy barb (P. conchonius) and black ruby barb (P. nigrofasciata) are long-established community-tank staples, and the golden barb (P. gelius), dwarf barb (P. phutunio), and odessa barb (P. padamya) are all regularly traded for their small size and bright breeding colour. That popularity sits alongside genuine conservation concern for some of the more range-restricted species — the Bandula barb (P. bandula), a Sri Lankan endemic known from a single small stream, is among the most narrowly distributed fish in the aquarium hobby's collective attention. Across the genus the atlas tally shows a mixed picture: 11 species Least Concern, but 13 Not Evaluated, 7 Vulnerable, 6 Endangered, and 2 Critically Endangered among the 44 covered, with 2 species carrying CARES conservation-priority status.