Native to the Mekong River drainage in Laos (where Vientiane province represents the upper limit of its range), Thailand, Cambodia, and Vietnam, and the Tapi, Chao Phraya, and Mae Klong systems in Thailand.

Type locality is ’22 kilometers upstream from Phnom Penh, Tonle Sap River, Kandal Province, Cambodia’.

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.

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.

L. chrysophekadion is also known as ‘black sharkminnow’. It continues to be available in the ornamental trade despite its patent unsuitability for the home aquarium, and an albino form has been selectively bred for the purpose.

It can be distinguished from other members of the genus by the following combination…

This species is extremely widespread and has been recorded from Pakistan, Nepal, most of India, Bangladesh, Myanmar and southern China.

Type locality is ‘Bengal and western provinces, India’.