The hillstream loaches or river loaches are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

, the Balitoridae, of small fish from

South South is one of the cardinal directions or Points of the compass, compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Pro ...

Southeast The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each sepa ...

and

East Asia East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea and ...

. The family includes about 202 species. They are sometimes sold as "lizardfish" or (in Germany) "flossensaugers". Many of the species are popular for aquaria, species in the genus ''

Sewellia ''Sewellia'' is a genus of fish in the family Balitoridae (River Loaches) found in Laos and Vietnam.Kottelat, M. (2012)Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei). ''Raffles Bulletin of Z ...

'' are most commonly sold in the aquaria trade. They have a number of similarities with the

Cobitidae Cobitidae, also known as the True loaches, is a family of Old World freshwater fish. They occur throughout Eurasia and in Morocco, and inhabit riverine ecosystems. Today, most "loaches" are placed in other families (see below). The family includ ...

, their sibling family of "

loach Loaches are fish of the superfamily Cobitoidea. They are freshwater, benthic (bottom-dwelling) fish found in rivers and creeks throughout Eurasia and northern Africa. Loaches are among the most diverse groups of fish; the 1249 known species of ...

es", such as multiple

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprinid ...

s around the mouth. They should not be confused with the

loricariids The Loricariidae is the largest family of catfish (order Siluriformes), with 92 genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are not ...

, which look similar but are a family of

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

. Most species are

rheophilic A rheophile is an animal that prefers to live in fast-moving water. Examples of rheophilic animals Insects *Many aquatic insects living in riffles require current to survive. *''Epeorus sylvicola'', a rheophilic mayfly species ( Ephemeroptera) ...

, living in swift, clear and well-oxygenated streams. Several species of the family live in fast-flowing

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

s or torrents and have modified ventral fins used for clinging to rocks. The

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Nemacheilinae has recently been separated as a distinct family,

Nemacheilidae The Nemacheilidae, or stone loaches, are a family of cypriniform fishes that inhabit stream environments, mostly in Eurasia, with one genus, ''Afronemacheilus'' found in Africa Africa is the world's second-largest and second-most populo ...

(stone loaches) and several genera have been separated into the family

Gastromyzontidae The Gastromyzontidae are a family of loaches native to China and Southeast Asia, where typically found in streams and rivers with a fast current. The family includes about 137 species in eighteen genera Genus ( plural genera ) is a taxonomic ...

References

Cypriniformes Freshwater fish of Asia {{Balitoridae-stub