Nam Theun

Generally considered to have an enormous natural range extending from Iran to Taiwan and Bali, with records existing from Iran, Iraq, Afghanistan, Pakistan, Nepal, India, Sri Lanka, Bangladesh, Bhutan, China, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Indonesia, and Singapore. However there exists significant evidence to suggest that C. gachua as currently understood represents a complex of similar-looking species, and a taxonomic review of the group is clearly required.

Native to the Mekong river system in Thailand, Laos, Vietnam, and Cambodia, including the Tonlé Sap basin. Type locality is 'Kemarat, Thailand', which corresponds to the Mekoong River in Khemmarat district, Ubon Ratchathani province, northeastern Thailand.

It is very similar to H. wetmorei but can be told apart by possessing yellow (vs. orange to red in H. wetmorei) pectoral, pelvic, and anal fins. It thus appears likely that yellow-finned fish marketed as H. wetmorei or 'lemon fin barb' in the ornamental trade are actually H. vernayi, with both species available on a regular basis.

Predominantly a riverine fish favouring clear, well-oxygenated, running water with substrates of sand or gravel and often present in rock and boulder-filled headwater streams. In the Mun River, close to the Pak Mun dam, Thailand, sympatric species included Hampala dispar, Cyclocheilichthys apogon, Osteochilus hasseltii,...

This species is traded for aquaria under various names including 'butterfly barb', 'mackerel barb', 'green-barred danio', and 'royal opsarius'. It can be told apart from other memb...

It can be further distinguished from congeners by the following combination of characters: small adult size; bright orange-red marginal bands on caudal-fin lobes in males; caudal-fin rounded and elongate; 5-7 dorsal-fin rays; relatively few (13-18) anal-fin rays without bony contact organs, the last ray branched; 6-8 pectoral-fin rays. Members of the family Adrianichthyidae are...

It can be distinguished from congeners by its small adult size and presence of a single solid dark midlateral stripe on the body, above which is a series of dark blotches forming a second stripe. In the similar but larger, T. schalleri the upper stripe is more variable depending on the mood of the fish, sometimes fading entirely.

This species is also referred to as 'royal knifefish' in the aquarium trade but arguably has no place in the ornamental hobby given its adult size and specialised requirements. It can be distinguished from congeners by presence of many small, dark spots on the anterior portion of the body which merge to form oblique, irregular stripes extending onto the anal and caudal fins posteriorly.

Endemic to the middle and lower Mekong River system in Laos, Thailand, Cambodia, and Vietnam. Its known range extends from Chiang Rai province, Thailand in the north to Kratie province, Cambodia in the south, and it occurs in several important tributary systems including the Sesan, Srepok, and Tonlé Sap. Type locality is 'Mekong River at Kemarat, Thailand'.

This species can be distinguished from congeners in Southeast Asia and China by the following combination of characters: plain brown body and fins, sometimes with 6-8 narrow, faintly distinct, longitudinal stripes; snout triangular in dorsal view, with small tubercules and without transverse groove...