Probably endemic to northern India, Bangladesh, and Nepal. Records from Sri Lanka, southern India, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, and Indonesia appear to represent other species.

Given the distribution of L. siamensis, it seems likely that many of the fish entering the aquarium trade are this species and not L. laubuca. The two species can be distinguished b…

It can be distinguished from other members of the genus by the following characters: dark longitudinal stripe on body, extending from eye to caudal peduncle; scattered tubercles present on lower jaw; 14½-16½ branched anal-fin rays; pelvic-fin long, reaching beyond anus.

It can be distinguished from other members of the genus by the following characters: lateral line absent or perforating only 2-5 scales; pharyngeal teeth hooked; body size small, not exceeding 30 mm SL; body depth less than 25 % SL; colour pattern comprising a dark bluish lateral stripe extending from the eye to the caudal peduncle, typically, but not always, forming 2-5 circular spots along its length.

This species is also known as ‘leaping barb’ and was once quite common in the ornamental trade but is now seldom seen.

It can be distinguished from other members of the genus by the following characters: bright blue spot on top of head; series of 4-5 short faint bars on anterior portion of body; 19-23½ branched anal-fin rays; body depth fits 2.1-2.9 times in SL.

L. siamensis can be distinguished from congeners by the following combination of characters: 39-42 scales in the lateral series; shoulder spot usually absent, but sometimes well-defined; body with longitudinal stripes formed by a spot on each scale; dorsal fin with dusky median stripe and no red coloration; caudal fin dusky, sometimes with reddish coloration, but no well-defined stripes; 20-23 circumpeduncular scales…

Different populations vary in appearance somewhat (see image of Salween specimen for example), and L. leptocheilus may turn out to represent a group of closely-related species rather than a single taxon. The population from the Cambodian Mekong has been considered to represent a distinct species, Labiobarbus lineatus, although that name is currently a synonym of L. leptocheilus following Kottelat (2013). It is widely used in the ornamental trade, however.

Known from the Pahang River system in southern Peninsular Malaysia, and the Greater Sunda Islands of Sumatra and Borneo. On the latter records exist from the Kapuas, Barito, and Mahakam watersheds in Kalimantan, the Indonesian portion of the island

Type locality is ‘Pangabuang, Lampong Province, Sumatra, Indonesia’.

Following Roberts (1997) G. ariza can be diagnosed by the following combination of characters: body with variably intense thin stripes dustributed mostly above the lateral line; larger individuals sometimes with a broad midlateral stripe; 32-35 lateral scales; 7-8/1/5-6 transverse scale rows; 8-9 branched dorsal-fin rays 8-9; 22-24+ 11-12=34(4), 35 (3) vertebrae; live colour pattern variable, overall dull dirty white to greyish, silvery or yellow.

Known with certainty from the Irrawaddy River system in Manipur state, India, and Myanmar, and the Salween watershed in eastern Myanmar and northwestern Thailand. Records from the Red River basin in Vietnam appear questionable.

Type locality is ‘Burma: Myitkyina District: Mali Hka basin: Phungin Hka;’.

This species can be distinguished by the following characters: juveniles with brown body and dark marking at base of caudal-fin; 37-42 + 3-4 lateral line scales; 11½ branched dorsal-fin rays; 7½ scale rows between lateral line and dorsal-fin origin; 20-25 predorsal scales; dorsal-fin relatively small with anterior branched rays shorter than head in juveniles, slightly longer than head in adults.