Lancang

The black-lined loach, Ambastaia nigrolineata, is a botiid loach from the Mekong drainage in southern China and Laos, and the Nan River in Thailand. It resembles its only congener A. sidthimunki but has a solid dark lateral stripe and another along the dorsal mid-line, with the vertical bars between them much less prominent. In Thailand it is considered endangered and appears in the national Red Book of threatened species.

Opsarius caudiocellatus is a cyprinid known only from the Salween in southern China, Myanmar and western Thailand, and the upper Mekong in Yunnan. It is named for the black round spot at the caudal-fin base, which with its black dorsal-fin rays separates it from similar congeners. It may have appeared in the aquarium trade, though probably not under the correct name, and inhabits well-oxygenated, moderate to fast-flowing rivers and streams.

Garra imberba is a cyprinid without barbels from the upper Yangtze, Mekong and Red River basins in southern China, and the upper Red in Vietnam. Records from the Salween system result from confusion with the similarly-named G. imberbis. With G. micropulvinus it is placed in the Semilabeoina, for which the name Ageneiogarra has been suggested. It tends to inhabit swiftly-flowing headwaters and tributaries.

Garra mirofrontis is a cyprinid native to the upper Mekong (Lancangjiang) basin in Yunnan province, China. It is characterised by a transverse groove on the snout directly in front of the eyes, and a bifurcate proboscis with a conical keratinised tubercle at each tip. A typical habitat is a strongly-flowing river about 25 m across with a predominantly rocky substrate.

Mystacoleucus lepturus is a riverine cyprinid known only from the upper Mekong basin in southern China, Laos and Thailand. It favours clear, well-oxygenated running water over sand or gravel. The body is relatively slender, with a black margin on the dorsal fin and many crescent-marked scales. Records from Vietnam and Hainan Island refer to other species. Like all Mystacoleucus it has a forward-pointing predorsal spine that can snag in a net.