Mystacoleucus

Mystacoleucus argenteus is a cyprinid from the Salween and middle Irrawaddy basins in Myanmar and western Thailand. It is occasionally marketed as 'Burmese rainbow barb' and differs from the similar M. obtusirostris in lacking black-edged scales on the body. Little has been published since Day's original description of 1888. Vigorous when feeding, it can upset slow-moving or timid tankmates.

Mystacoleucus atridorsalis is a pelagic cyprinid considered endemic to the lower Mekong basin in Laos, Thailand and Cambodia. It favours flowing lowland river channels and moves into flooded forest during the wet season. A triangular blotch at the tip of the dorsal fin helps separate it from congeners, and like all Mystacoleucus it has a forward-pointing predorsal spine that can become entangled in an aquarium net.

Mystacoleucus chilopterus is a pelagic cyprinid from the middle Mekong, Chao Phraya and Mae Klong basins in Laos and Thailand. It favours flowing lowland rivers and swiftly-flowing forest streams with rock and gravel. The anal fin has a concave margin and the dorsal and caudal fins black margins, and like all Mystacoleucus it has a forward-pointing predorsal spine that can become entangled in an aquarium net.

Mystacoleucus ectypus is a pelagic cyprinid from the middle Mekong basin in Laos and Thailand, and may be endemic to the Khorat Plateau. It inhabits flowing lowland rivers and swift tributary streams with rock and gravel. It has a triangular blotch at the tip of the dorsal fin but no black fin margins or crescent-shaped scale markings, and like all Mystacoleucus it has a forward-pointing predorsal spine that can snag in a net.

Mystacoleucus greenwayi is a riverine cyprinid from the middle Mekong basin in Thailand and Laos and the Chao Phraya watershed. It favours clear, well-oxygenated running water over sand or gravel, often in rock and boulder-filled headwater streams. A schooling fish, it should be kept in a group of six or more alongside similarly-sized cyprinids, loaches and other riverine fishes, and like all Mystacoleucus it has a forward-pointing predorsal spine that can snag in a net.

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.

Mystacoleucus obtusirostris is a riverine cyprinid found from Myanmar and southwestern China to Vietnam, Borneo, Sumatra and Java. Referred to as M. marginatus for decades, it is the most widely distributed member of the genus, and populations vary somewhat in colour pattern. It is occasionally marketed as 'Burmese rainbow barb'. A group of six or more is the smallest to consider, and like all Mystacoleucus it has a forward-pointing predorsal spine that can snag in a net.