Distribution
Fish in the genus ''Sewellia'' occur in the Sekong River, a tributary of the Mekong river. The Sekong river drains large parts of central and southeast Laos as well as southern Vietnam.Habitat and Ecology
''Sewellia'' are found in the rapids and riffles of steep gradient 'hill streams', hence the common name Hillstream Loache. Due to their steep gradients these streams have high current velocities, Sewellia are known to inhabit streams with current velocities exceeding 1 m · s−1 in some habitats. Sewellia feed mainly on micro to macro sized aquatic invertebrates that inhabit the periphyton attached to submerged rocks.Sexual Dimorphism
''Sewellia'' are sexually dimorphic, males have soft elevated patches of fine tubercles on the anterior part of pectoral-fin rays 1-6, females do not. '' Sewellia lineolata'' are common in the aquaria trade, they are sexed based on differences in shape, at sexual maturity males tend to be more streamlined while females are somewhat broad; the beginning of the pectoral fins occurs at a much sharper angle in the male than females, females have pectoral fins that begin in a more rounded fashion (softer angle).Species
There are currently 14 recognized species in this genus: * '' Sewellia albisuera'' Freyhof, 2003 * '' Sewellia analis'' H. D. Nguyễn & V. H. Nguyễn, 2005 * '' Sewellia breviventralis'' Freyhof & Serov, 2000 * '' Sewellia diardi'' T. R. Roberts, 1998 * '' Sewellia elongata'' T. R. Roberts, 1998 * ''Conservation Status
•''Sewellia albisuera-''IUCN Critically Endangered •''Sewellia analis-''IUCN Not Evaluated •''Sewellia breviventralis'' - IUCN Critically Endangered •''Sewellia diardi-''IUCN Data Deficient •''Sewellia elongata-''IUCN Near Threatened •''Sewellia hypsicrateae-''IUCN Not Evaluated •''Sewellia lineolataSewellia '' ''-''IUCN Vulnerable •''Sewellia marmorata-'' IUCN Endangered •''Sewellia medius-''IUCN Not Evaluated •''Sewellia monolobata-''IUCN Not Evaluated ''Sewellia '' •''Sewellia patella-'' IUCN Endangered •''Sewellia pterolineata-''IUCN Endangered''Sewellia '' •''Sewellia speciosa-''IUCN Least Concern •''Sewellia trakhucensis-''IUCN Not Evaluated ''Sewellia ''References
{{Taxonbar, from=Q11949615 Freshwater fish genera Gastromyzontidae Taxa named by Sunder Lal Hora