Native to the central Amazon basin with records existing from the Madeira, Branco, Trombetas, and Tapajós river drainages, plus the Rupununi basin in Guyana. Although an affluent of the rio Essequibo and thus not officially part of the Amazon basin, the latter is connected to the rio Takutu, a tributary of the upper rio Branco, during the annual wet season.

Type locality is given by Fowler as ‘Rio Madeira about 200 miles east of W. Long. 62°20′, Brazil’.

Endemic to a handful of tributary streams within the upper Chao Phraya river system in northern Thailand. Six populations are known to date, with the majority lying inside the Doi Chiang Dao Wildlife Sanctuary.

Some of its habitats are under threat by over-grazing, deforestation, deliberate forest fires, and collection for the aquarium trade.

Appears restricted to highly-oxygenated, fast-flowing riffles of small-to-medium sized streams. These typically contain clear water with substrates of gravel, rocks, boulders, and bedrock with no aquatic plants.

This is the smallest member of the genus and rarely traded in numbers, though it’s a relatively common contaminant among shipments of wild fishes from Manaus. Unlike other Nannostomus spp. it does not exhibit a specific colour pattern of spots or bars at night-time, rather displaying an overall paleness.

The family Lebiasinidae is included in the order Characiformes and sometimes split into the nominal subfamilies Lebiasininae a…

Fishes which inhabit similar biotopes in nature constitute the best options, especially peaceful, open water-dwelling cyprinids since the presence of one or two schools can make a visible difference to the confidence of this naturally reclusive loach.

Barilius spp. are near-exclusive surface-feeders preying mostly on flying insects in nature with some small fishes and benthic invertebrates probably taken as well but in the aquarium they’re largely unfussy and will accept most foods.

Like many fishes that naturally inhabit running waters it’s intolerant to the accumulation of organic wastes and requires spotless water at all times in order to thrive. It also does best if there is a high proportion of dissolved oxygen and moderate degree of water movement so external filters, powerheads, airstones, etc., should be employed as necessary.

This species is feisty and largely unsuitable for the general community aquarium. This is not to say it must be kept alone, rather that tankmates must be selected with care and proper research.

Slow-moving or long-finned species should certainly be omitted because they’re likely to struggle with the necessary level of water movement and may end up with nipped fins.

This species has been widely regarded as a member of the genus Nemacheilus since the late 1970s with the vast majority of subsequent authors considering it as such, although in the aquarium hobby it’s more commonly referred to Schistura.

Type locality is given as ‘Babianjiang River, 24°20’N, 100°10’E, Jingdong County, Yunnan Province, China’. The Babianjiang joins the Mengyejiang River to form the Langmajiang River, a tributary of the Lixianjiang (Black River) within the Red River basin.