Thailand

The Chinese false gudgeon, Abbottina rivularis, is a small bottom-dwelling cyprinid native to China, the Korean peninsula and southern Japan. It has been widely introduced elsewhere, including the Mekong and Salween basins, Taiwan, Turkmenistan and Kyrgyzstan, and is considered invasive. It has started to appear in the aquarium trade and should never be released into natural waters outside its native range.

Acanthopsoides molobrion is a dwarf horse-faced loach from Borneo, Peninsular Malaysia and southern Thailand. Like others in the genus it lives in flowing, clear-water river channels over sand, fine gravel or mud, and needs a soft, sandy substrate because it spends some of its time completely buried. Several Acanthopsoides in the trade have proven very tricky to identify. This one has 10 to 15 mid-dorsal markings and three bands in the caudal fin.

The horseface loach, Acantopsis dialuzona, is a cobitid loach from Sumatra, Borneo, Java and Peninsular Malaysia, and possibly Thailand. Most literature lists it as A. choirorhynchos, which Kottelat treats as a junior synonym, and few if any fish in the trade come from near the type locality, so they may represent an unidentified species. Juveniles are exported in large numbers but adults are uncommon in the hobby, and it needs soft sand to bury in.

The falcate chameleon catfish, Acrochordonichthys gyrinus, is an akysid catfish known only from the Yom River, Chao Phraya basin, northern Thailand. A concave rear margin to the pectoral fins separates it from the rest of the A. ischnosoma group. When stressed it can secrete a milky substance from the axillary pore that quickly kills other fishes in an aquarium, and smaller tankmates will be eaten.

The Asian banjo catfish, Acrochordonichthys rugosus, is an akysid catfish from Java, Sumatra, Borneo, Peninsular Malaysia and southern Thailand. The most commonly encountered member of the genus in the trade, it is still by no means common, and body colouration varies widely even among fish from a single locality. Like its congeners it can secrete a milky substance from the axillary pore when stressed, and this can quickly kill other fishes in the confines of an aquarium.

The Mae Klong chameleon catfish, Acrochordonichthys septentrionalis, is an akysid from western Thailand, possibly endemic to the Mae Klong drainage. It differs from other members of the A. ischnosoma group in its almost uniformly cream body with a few small brown spots, though colouration in the genus is variable. Like its congeners it can secrete a milky substance from the axillary pore when stressed, and this can quickly kill other fishes in an aquarium.

Hendrickson's stream catfish, Akysis hendricksoni, is a small akysid catfish from much of Peninsular Malaysia and the extreme south of Thailand. One of the few members of the family exported for the hobby, it grows to around 50 mm SL and spends some of its time buried in sand with only the eyes showing. Colour pattern varies with locality, and like many fishes from running water it is intolerant of organic pollutants and needs spotless water.

The spotfin stream catfish, Akysis maculipinnis, is a small akysid catfish from Chanthaburi Province in eastern Thailand. Its range apparently extends into Cambodia. Among the smaller members of the family at around 35 mm SL, it has been exported for the hobby. It spawns above the substrate in flowing water with no parental care, and the adults are avid egg-eaters, so the eggs must be protected if fry are to be raised.

The Kra stream catfish, Akysis pulvinatus, is a small akysid catfish from southern Thailand. Known from streams on the western side of the Kra Isthmus and the upper Tapi basin, it grows to around 30 mm SL and has been exported for the hobby on an extremely limited basis. It most resembles A. vespa, and differs in its longer adipose fin base, deeper caudal peduncle and a caudal fin with the lower lobe longer than the upper.

The variable stream catfish, Akysis varius, is a small akysid catfish from the Mekong drainage in Laos, Thailand and Cambodia. The number of serrations on its pectoral spine varies, and in contrast to other Akysis with serrated spines, the larger specimens examined had fewer or none. Members of the genus live almost exclusively in swiftly flowing streams and rivers over sand, gravel and rocks.

The orange-banded stream catfish, Akysis vespa, appears endemic to headwaters of the Salween basin on the border between Myanmar and Thailand. One of the few members of the family exported for the hobby, it is also sold as 'wasp catfish' or 'orange micro bumblebee catfish'. Its yellow markings normally form wide bands, a pattern rarely seen in congeners, and the yellow on the snout extends to the base of the nasal barbels.

The black-lined loach, Ambastaia nigrolineata, is a botiid loach from the Mekong drainage in southern China and Laos, and the Nan River in Thailand. It resembles its only congener A. sidthimunki but has a solid dark lateral stripe and another along the dorsal mid-line, with the vertical bars between them much less prominent. In Thailand it is considered endangered and appears in the national Red Book of threatened species.

The dwarf chain loach, Ambastaia sidthimunki, is a small botiid loach from the Mae Klong basin in western Thailand and the Ataran drainage in Myanmar. Older records from the Yom River, Laos and Cambodia refer to A. nigrolineata. Gregarious, it should be kept in a group of at least five or six and preferably ten or more, and reports conflict on whether it stays peaceful with sedentary or long-finned fishes.

The princess carplet, Amblypharyngodon chulabhornae, is a small cyprinid from Thailand and the Mekong system in Laos, Vietnam and Cambodia. It favours wetlands and marginal zones with little water movement and plenty of aquatic and floating vegetation,. Almost unknown in the hobby, it turns up as occasional bycatch among shipments of other fishes. A very peaceful schooling fish, it should be kept in a group of at least 8 to 10.

Badis khwae is a badid that appears to be endemic to the Khwae Noi River basin in western Thailand, close to the border with Myanmar. It is most easily confused with B. ruber and B. siamensis, but lacks the rows of dark spot-like markings both have on the flanks. Its restricted range means it is unlikely ever to be available in large numbers. It lives in small forest streams with sluggish to moderate flow, usually in marginal areas or still pools.

The Burmese badis, Badis ruber, is a badid common throughout much of lowland Myanmar, from the Ayeyarwady and Sittaung south to the Tenasserim. Among the better known Badis in the hobby, it is also traded as 'red badis' and appears in older literature as Badis badis burmicanus. It differs from B. khwae and B. siamensis in its rows of vertically arranged dark flank markings and relatively large caudal peduncle blotch. It tends to inhabit lentic biotopes such as roadside ditches and small, well-vegetated creeks.

Badis siamensis is a badid endemic to Peninsular Thailand, collected only from river systems draining the western coastline. It is most easily confused with B. khwae and B. ruber, but has rows of horizontally arranged dark markings on the flanks, and its caudal peduncle marking is reduced or missing. Poorly documented, it was known for a number of years as Badis badis siamensis and is labelled so in older literature. Its habitat is unconfirmed.

The white-whisker lancer, Bagrichthys majusculus, is a bagrid catfish from the Mekong and Chao Phraya river systems in Thailand and Laos. Described from the Mun River in eastern Thailand, it is most similar to B. macracanthus and B. vaillantii and differs from both in its longer pectoral-fin spines. It inhabits large, turbid, slow rivers and moves into flooded riparian zones to spawn in the wet season. A shy, nocturnal fish, it is territorial towards other bottom-dwellers, especially its own kind.

Bagrichthys obscurus is a bagrid catfish from the Chao Phraya, Bang Pakong and Mekong watersheds in Thailand, Cambodia and Vietnam. One of the lancers, named for the extended dorsal spine in several members of the genus, it has a uniformly brown body with no pale stripe or blotches, a small mouth and a relatively short dorsal spine. It inhabits large, turbid rivers with slow flow, and is shy, nocturnal and territorial towards other bottom-dwellers.

Balitoropsis zollingeri is a balitorid loach described from Java and recorded from Sumatra, Borneo, Peninsular Malaysia, Thailand, Laos and Cambodia. An obligate dweller of swiftly flowing streams and headwaters, it lives on riffles and runs over gravel, rocks and bedrock carpeted with biofilm. It needs clean, well-oxygenated water with strong turnover in the aquarium. It lives in aggregations in nature and is less bold when kept singly or in small numbers, so a group of six or more is best.

Barbodes aurotaeniatus is a small cyprinid from the middle and lower Mekong basin in Laos, Vietnam, Cambodia and Thailand. Uncommon in the aquarium trade, it has a single pair of maxillary barbels, lacking the rostral barbels of other Barbodes, and usually four small vertical black markings on the flanks. It inhabits streams, irrigation canals and ditches, and is apparently very peaceful, best kept in a mixed-sex group of 6 to 10.

The spotted barb, Barbodes binotatus, is a cyprinid ranging from Myanmar and Thailand through the Greater Sunda Islands to the Philippines. So ubiquitous across its range that it's often called simply 'common barb', it occurs from sea level to at least 2000 m in habitats from fast-flowing hill streams to irrigation canals and floodplain ponds. The basic pattern of a dark spot at the dorsal-fin origin and another on the caudal peduncle varies with origin.

The spanner barb or 'T-barb', Barbodes lateristriga, is a cyprinid from peninsular Thailand, Peninsular Malaysia, Singapore, Sumatra and Java. Its colour pattern varies with locality, and the form most commonly seen in the trade corresponds most closely to fish from Johor. The species may prove to be a complex of closely-related taxa. Quite boisterous, it can intimidate more timid species with its size and activity, especially at feeding times.

The red-tailed tinfoil barb, Barbonymus altus, is a large cyprinid from Thailand, Laos, Cambodia and Vietnam. One of two species traded as 'tinfoil barb', it is usually sold at 50 to 75 mm with little information on its eventual size, and long-term care is beyond the resources of most hobbyists. Natural fish lack the black stripe along each caudal-fin lobe seen in B. schwanefeldii, and adults have a golden or bronze hue.

Barbonymus gonionotus is a large cyprinid with an enormous distribution across Southeast Asia, from the Mekong to Java and Sumatra. It inhabits larger, slow-moving rivers and their floodplains, moving into flooded forest to feed and spawn, and is increasingly found in man-made canals and lakes. Plain grey caudal and dorsal fins and pale yellow pelvic and anal fins separate it from congeners. Populations in Peninsular Malaysia appear to be introduced.

The tinfoil barb, Barbonymus schwanefeldii, is a large cyprinid found across much of Southeast Asia, from the Mekong to Borneo and Sumatra. Usually sold at 50 to 75 mm, it grows to 355 mm SL, and tinfoil barbs are among the species most often returned to shops having outgrown their aquarium. Selectively-bred 'golden' and 'blushing' strains exist, and the species has also been subjected to artificial dyeing.

Batasio feruminatus is a small bagrid catfish from the Ataran River system in southern Myanmar, to which it is possibly endemic. Some Ataran tributaries extend across the border into Thailand. Like its congeners it is an obligate inhabitant of shallow, fast-flowing, highly-oxygenated headwater streams. B. feruminatus alone in the genus has both an oblique dark bar in front of the dorsal fin and a thin black midlateral stripe.

Batasio fluviatilis is a small bagrid catfish from southern Thailand and Peninsular Malaysia, below the Isthmus of Kra. Like its congeners it is an obligate inhabitant of shallow, fast-flowing, highly-oxygenated headwater streams, and it is largely unsuitable for the 'general' community aquarium. Batasio havmolleri is considered a junior synonym, and this is one of the Batasio species that has been spawned in captivity.

Batasio tigrinus is a small bagrid catfish that appears endemic to the Khwae Noi basin, often called the River Kwai, in western Thailand. The Khwae Noi is part of the larger Mae Klong watershed. Like its congeners it is an obligate inhabitant of shallow, fast-flowing, highly-oxygenated headwater streams, and it is largely unsuitable for the 'general' community aquarium.

The Java combtail, Belontia hasselti, is a labyrinth fish from peninsular Thailand, Peninsular Malaysia, Singapore, Sumatra, Borneo and Java. Also known as the 'Malay combtail', it mostly inhabits acidic forest peat swamps with little water movement. It differs from its only congener, B. signata, in its brownish grey body and the mosaic pattern in its unpaired fins. Growing to 200 mm SL, it will eat very small fishes and is not recommended for the average community aquarium.

The crescent betta, Betta imbellis, is a labyrinth fish thought to be native to southern Thailand, Peninsular Malaysia and northern Sumatra. It has been line-bred for aggression in southern Thailand and hybridised with B. splendens and other congeners for the ornamental trade, producing colour forms that do not occur naturally. Introduced ornamental forms and other Betta spp. are having an adverse effect on the genetic integrity of some wild populations.

Betta kuehnei is a paternal mouthbrooding labyrinth fish from Kelantan state, northeastern Peninsular Malaysia, and neighbouring Narathiwat, Thailand. A member of the B. pugnax complex, it has a rounded caudal fin in both sexes and adult males carry intense blue or bluish-green iridescence on the head and throat. It may be conspecific with B. sp. 'Satun'. The type locality is a shady, clear forest stream with beds of Cryptocoryne cordata.

Betta mahachaiensis is a bubble-nesting labyrinth fish known only from a handful of coastal localities around Bangkok in central Thailand. The only member of the genus to occur exclusively in brackish water, it inhabits tidal coastal swamps and builds its nests among nipa palms. Once considered a hybrid, it has been confirmed as a distinct species, and most of its habitats are under extreme threat from the expansion of Bangkok.

Betta pallida is a small paternal mouthbrooding labyrinth fish described from Narathiwat province at the southern tip of Peninsular Thailand. Known as B. sp. 'southern Thailand' before its description, it belongs to the B. picta group and has a yellowish head and body with three lateral stripes. It has been collected from a shallow, slow-moving creek with clear, slightly tannin-stained water over leaf litter.

Betta pi is a large paternal mouthbrooding labyrinth fish from peat swamps in southern Thailand and the states of Kelantan and Terengganu, Malaysia. A member of the B. waseri group, it is named for the dark marking on the throat shaped like the Greek letter pi. It is not among the more aggressive members of the genus and can be maintained in a pair or group.

Betta prima is a paternal mouthbrooding labyrinth fish from south-eastern Thailand and the Mekong basin in Cambodia and Laos. Before its description it was widely misidentified as B. pugnax or B. taeniata, and not all authors place it in the B. pugnax complex. It inhabits clear-water forest swamps and streams that can be still or swift, sheltering among marginal roots, leaf litter and vegetation.

Betta siamorientalis is a small bubble-nesting labyrinth fish from eastern Thailand, western Cambodia and Vietnam. It lives among submerged vegetation in marshes, flooded fields and rice paddies. Before its description in 2012 it was considered a colour form of B. imbellis known as 'black imbellis', and it has also been confused with B. splendens, but DNA analysis showed it to be distinct. Males have a dark brown to black body and a black opercle with two reddish vertical bars.

Betta simplex is a mouthbrooding labyrinth fish known only from Krabi province in southern (peninsular) Thailand. Its habitats lie in a karstic area of limestone sinkholes with clear, neutral to alkaline water at pH 7.0 to 7.4. It is most abundant in a small ditch draining the pools that often dries out, leaving some fish in shallow remnant pools. A population from near Ao Luek has appeared in the hobby as B. simplex 'type 2'.

The emerald betta, Betta smaragdina, is a bubble-nesting labyrinth fish from the Khorat Plateau in eastern Thailand and Mekong tributaries in Laos. It inhabits still and sluggish waters such as rice paddies, swamps and roadside ditches. It has been line-bred for aggression in eastern Thailand, and selectively bred and hybridised for the ornamental trade into colour forms that do not occur naturally. Wild populations vary in the extent of red or green patterning and are often labelled by locality.

The Siamese fighting fish, Betta splendens, is a labyrinth fish from central Thailand, native to rice paddies, swamps, ditches and other still waters. The wild form is rarely seen in the hobby, but countless ornamental strains exist that vary tremendously in colour, finnage and quality. Its care requirements and disposition mean it is best kept alone, and it is not recommended for the standard community aquarium.

The dwarf rasbora, Boraras maculatus, is a miniature cyprinid from Peninsular Malaysia, southern Thailand, eastern Sumatra, Singapore and Bintan. It inhabits blackwater streams and rivers associated with forest peat swamps, where the water is very soft and acidic. Colour pattern varies between populations, some forms showing more intense red than others. It is most similar to B. naevus, in which the red body colouration does not extend into the head.

Boraras micros is a tiny cyprinid from the Mekong basin in northeastern Thailand, recorded in Nong Khai, Udon Thani and Sakon Nakhon provinces. Growing to only 13 mm SL, it inhabits shallow, clear, densely vegetated swamps, marshes, floodplains and rice paddies. Poorly documented and rarely seen in the trade, it has a rather plain pattern, and fish sold as B. micros var. 'red' or 'strawberry rasbora' are always B. maculatus, B. brigittae or B. naevus.

Boraras naevus is a miniature cyprinid known only from the lower Tapi river drainage in Surat Thani province, southern (peninsular) Thailand. Before its description it was traded as B. sp. 'micros', 'red micros', 'Petch Noi' and 'strawberry rasbora', and it is exported only sporadically. It lives in shallow, clear swamps and marshes. Males have an anterior flank blotch much larger than that of females, a feature unique to this species within the genus.

Boraras urophthalmoides is a miniature cyprinid from southern and central Thailand, Cambodia and Vietnam, including the moats of Angkor Wat. It inhabits shallow, clear, vegetated swamps, marshes, floodplains and rice paddies. Some populations develop an orange-red stripe that leads to confusion with B. brigittae, but B. urophthalmoides is smaller, with a distinct round, dark blotch on the caudal peduncle and a long, unbroken lateral stripe. It is sometimes sold as the 'exclamation-point rasbora'.

The polka-dot loach, Botia kubotai, is a botiid loach that appears to be endemic to headwaters of the Salween basin in Myanmar and Thailand. It was traded before it was described and is still sold as 'angelicus', 'Burmese border loach' and 'marbled loach', among other names. Juveniles are often confused with B. histrionica, but the dark bars in B. kubotai split at a young age.

The Mekong bumblebee goby, Brachygobius mekongensis, is a tiny goby from the central and lower Mekong, including the Tonlé Sap system. It is apparently restricted to slow-moving or standing fresh water such as marshes, seasonal swamps and floodplains with dense aquatic vegetation. Narrow, often broken dark bars on a pale background separate it from the most similar species, B. nunus. It is poorly known in the hobby, and other species are sold under its name.

Brachygobius xanthomelas is a small bumblebee goby recorded throughout much of Peninsular Malaysia and southern Thailand. It lives in lowland freshwater swamps, streams and forest peat swamps and, unlike most congeners, does not appear to occur in brackish water. The name is widely misapplied to an unidentified member of the genus, the fish in most online images, which has a dark marking at the front of the first dorsal-fin base where B. xanthomelas is colourless.

The eyespot rasbora, Brevibora dorsiocellata, is a small cyprinid from southern Thailand, Peninsular Malaysia, Borneo and Sumatra. It is also traded as the 'green-eyed', 'emerald-eyed' or 'hi-spot' rasbora. The common, commercially produced form is plain-coloured with a greenish-blue reflective patch in the eye, while a probably wild-caught form seen from time to time has russet red at the base of the tail. Some Bornean records may refer to B. cheeya.

The olive flathead gudgeon, Butis amboinensis, is a nocturnal ambush predator from the eastern Indian Ocean to the West Central Pacific. It inhabits brackish estuaries, lagoons and mangroves, entering tidal freshwater rivers to an extent, and often aligns itself with solid surfaces or swims upside-down. It is occasionally exported as bycatch and differs from congeners in lacking enlarged outer teeth and scales on the cheek. It is territorial and should probably be kept singly.

The crazy fish, Butis butis, is a flathead gudgeon of coastal and brackish waters across the Indo-Pacific, from eastern Africa to Fiji. The most commonly traded member of the genus, it has many other names, including crocodile fish, duckbill sleeper and upside-down sleeper. A nocturnal ambush predator, it often swims upside-down, and it is territorial and not sociable with conspecifics, so is best kept singly.

The redeye puffer, Carinotetraodon lorteti, is a small freshwater puffer from the lower Mekong basin and the Chao Phraya watershed in Indochina. It inhabits slow-moving to standing water in shady forest streams, minor tributaries and floodplains, often among dense vegetation. It tends to bite the fins of tankmates and is territorially aggressive, so is best kept alone, though a group can be kept with enough space and a suitable layout.

Chagunius baileyi is a large cyprinid endemic to the Salween and Sittaung river basins in Myanmar and western Thailand. Rarely kept, it turns up occasionally as bycatch among shipments of wild fish from Thailand and Myanmar. It looks almost identical to C. chagunio and C. nicholsi, and the three are most easily separated by collection details since their ranges do not overlap. At up to 200 mm it needs a very large tank with plenty of open swimming space.

The Indian glass fish, Chanda ranga, is a small ambassid from South and Southeast Asia, with translucent skin that shows its bones and organs. For many years it was injected with luminous dyes on Asian fish farms and sold as 'painted' glass fish, and most injected fish do not survive more than a few months. It is found most often in freshwater, frequently soft and acidic, and needs no added salt. Parambassis lala and C. siamensis are often imported under its name.

The dwarf snakehead, Channa gachua, is a snakehead recorded across an enormous range from Iran to Taiwan and Bali. There is significant evidence that C. gachua as currently understood is a complex of similar-looking species in need of taxonomic review. A mouthbrooder bred regularly in captivity, it can share a well-chosen community with peaceful fishes too large to be prey, but populations should not be mixed as some may hybridise.

The forest snakehead, Channa lucius, is a predatory snakehead from Indochina, Peninsular Malaysia and the Greater Sunda Islands. Also referred to as the 'splendid' or 'shiny' snakehead, it occurs on Sumatra, Borneo and Java, grows to 400 mm SL and favours forest swamps and tributaries. Like others in the genus it breathes atmospheric air, and it needs a dimly-lit tank with plenty of cover and a tightly-fitting lid, since Channa spp. are notorious for their ability to escape.

The black snakehead, Channa melasoma, is a snakehead from southern Thailand, Peninsular Malaysia, Singapore, Borneo, Sumatra and the Philippines. It can be told apart from the similar C. baramensis, once considered a synonym, by lacking a black spot in the centre of many body scales and a barred caudal fin. In nature it appears to favour clear forest streams with mud and leaf litter, but it has also been recorded from acidic blackwater in peat swamp forest.

Channa sp. 'fire and ice' is an unidentified snakehead apparently collected in the border region between Myanmar and western Thailand. Named for the red and blue colour pattern on its head, it first appeared in the aquarium trade in 2009 and has also been sold as C. sp. 'cherry'. A paternal mouthbrooder, it has been bred in captivity, and young fish turn highly aggressive towards one another as they mature.

Crossocheilus atrilimes is one of several near-identical cyprinids traded as the Siamese algae eater, native to the Mekong and Chao Phraya drainages. Telling it apart from C. langei and the undescribed C. sp. 'citripinnis' takes a combination of characters, including a black stripe running to the tip of the caudal fin that broadens and pales when the fish spar. A shoaling fish of flowing streams, it needs spotless, well-oxygenated water and a group of six or more.

Crossocheilus langei is a cyprinid from Borneo, Peninsular Malaysia and Thailand, one of several near-identical fish sold as the Siamese algae eater. The trade name 'Crossocheilus siamensis' used for these fish is not valid. C. langei can be told apart by a dark blotch in front of the anal fin and a lateral line running straight through the dark body stripe.

Usually offered as the reticulated or fishnet flying fox, Crossocheilus reticulatus is a cyprinid from the Chao Phraya and Mekong basins. A silvery body, dark-edged scales and a dark caudal peduncle blotch set it apart from similar congeners. Patterning varies with collection locality, which led to several names now treated as synonyms. A fish of flowing streams, it is best kept in a group of six or more, since weaker individuals can be bullied in smaller numbers.

The beardless barb, Cyclocheilichthys apogon, is a cyprinid ranging from Myanmar to Vietnam and south via Peninsular Malaysia to Borneo and Sumatra. Also sold as 'skinhead barb', it lacks barbels and has a black blotch at the caudal-fin base plus rows of dark spots along the scale rows. It favours slower-moving or still water and grazes the biofilm on submerged roots and branches. Rarely imported in numbers, it most often arrives as bycatch.

Cyclocheilichthys armatus is a cyprinid ranging from the Mekong region through Thailand and Peninsular Malaysia to Borneo, Sumatra and Java. It forages from mid-water to the bottom of rivers in the dry season and is thought to migrate into flooded forest to breed. Rarely imported in numbers and most often arriving as bycatch, it makes a peaceful, unusual addition to larger aquaria in a group of at least six.

Cyclocheilichthys heteronema is a cyprinid ranging from Myanmar east to Vietnam and south to Peninsular Malaysia, Borneo and Sumatra. Its fimbriated barbels, extended downwards while it browses, are unique in the genus. It doesn't appear to be common in nature, with most records from Peninsular Malaysia, and it reaches the trade only as occasional bycatch. Very peaceful but retiring, it is easily outcompeted by boisterous tankmates.

Cyclocheilichthys lagleri is a cyprinid from the Chao Phraya river system in central Thailand and the lower Mekong basin in Thailand and Cambodia. It is observed mostly on low-altitude floodplains and may migrate into inundated areas to spawn. Lacking barbels entirely and with 20 circumpeduncular scales, it makes a peaceful, unusual addition to larger aquaria in a group of at least six.

Cyclocheilichthys repasson is a cyprinid with an enormous range, from the Mekong region and Myanmar through Peninsular Malaysia to Borneo and Sumatra. It grows to around 280 mm SL and favours slower-moving or still water, grazing the biofilm on submerged roots and branches. It is not often seen in the hobby. Most populations have a dark caudal peduncle spot, stripes formed by dark markings on the scales, and two pairs of barbels.

The pearl danio, Danio albolineatus, is a small cyprinid recorded from Myanmar and Indochina south to Peninsular Malaysia and Sumatra. Colour and patterning differ between localities, and doubts remain whether it is a single species or a group of closely related fish. Wild examples are rare in the trade, with most produced commercially in South East Asia or eastern Europe, and some of the fish traded are likely to be hybrids with D. roseus.

The blue danio, Danio kerri, is a small cyprinid from islands and the adjacent mainland of south-western Thailand. It was described from Phang Nga province and has since been recorded from Phuket, Ko Lanta, Langkawi, Krabi and Ranong. Base body colour is powdery-blue in the north of its range and more yellowish in the south, with pinkish-yellow lateral stripes. It inhabits clear forest streams over rocks and gravel, and can be hard to find in aquarium shops.

The rosy danio, Danio roseus, is a small cyprinid from the Mekong basin in northern Thailand and Laos, also recorded in northern Myanmar. Colourful, hardy and usually cheap, it has proved very popular and is sometimes sold as 'purple passion danio'. It is very similar to D. albolineatus sensu stricto but has a slimmer body, shorter rostral barbels and no dark stripes on the rear half of the body. Many fish in the hobby are thought to be hybrids of the two.

The silver tiger perch, Datnioides polota, is a tiger perch widely distributed in southeastern Asia, from India and Bangladesh east to Indonesia. Mostly found in brackish habitats such as estuaries, mangroves and coastal lagoons, it has a highly variable colour pattern with up to 7 dark bars. The name D. quadrifasciatus is sometimes applied to it, but that name is a junior homonym and polota takes precedence.

The Mekong tiger perch, Datnioides undecimradiatus, is known only from the middle and lower Mekong basin in Thailand, Laos, Cambodia and Vietnam. An efficient, largely piscivorous predator of large, deep lowland rivers, it is marked with 4 relatively thin dark bars. The names 'Siamese tiger fish' and 'gold datnoid' are sometimes applied to it, but more typically belong to D. pulcher.

The striped barb, Desmopuntius johorensis, is a cyprinid from southern Thailand, Peninsular Malaysia, Singapore, Sumatra and Borneo. Juveniles have 4 dark vertical bars and develop 5 or 6 broad lateral stripes as they grow, a pattern change shared with D. gemellus and D. trifasciatus. Before Kottelat (1992) it was referred to as Puntius eugrammus, while the name 'Puntius johorensis' was misapplied to D. hexazona. It lives mainly in peat swamps and black water streams.

Devario acrostomus is a devario from the Nam Leuk drainage in Vientiane Province, Laos, and has also been recorded in northeastern Thailand. It first appeared in the hobby in early 2011. It looks like D. aequipinnatus and allies at first glance, but has a sharp, upwardly-pointing mouth, a snout longer than the eye diameter, long rostral barbels and strongly pigmented body patterning. Above Tad Leuk falls its habitats have clear water under forest cover.

Devario chrysotaeniatus is a devario from the upper Mekong watershed in Yunnan, southwestern China, northern Laos and northern Thailand. It first appeared in the hobby in 2005 and is rarely seen, probably because its natural waters lie outside the range of most commercial collectors. Its flank pattern is indistinct: a few short, thin horizontal stripes, a dark stripe along the back and a spot behind the gill opening.

Devario laoensis is a devario from the upper Mekong watershed in northwestern Laos and northern Thailand. Its dark P stripe starts faint around mid-body and becomes thicker and darker towards the caudal-fin base. Among congeners it is most similar to D. chrysotaeniatus, in which the P stripe extends to the end of the caudal-fin rays. Its habitats lie at relatively high altitude and are likely to be hill streams and small rivers.

The queen 'danio', Devario regina, is a deep-bodied devario probably restricted to western and southern Thailand and northern Peninsular Malaysia. It belongs to a group of similar-looking congeners with a blue-and-yellow colour pattern. Most commonly it inhabits submontane hill streams and upper parts of small rivers with clear, well-oxygenated water.

Discherodontus ashmeadi is a cyprinid apparently native to the Mae Klong and Mekong river basins in Thailand, Laos and Cambodia. The type species of its genus, it inhabits clear, fast-flowing minor rivers and forest streams. Like its congeners it is notoriously delicate and difficult to ship: it goes into shock and loses scales very easily when removed from the water, and damaged areas tend to become infected.

Discherodontus halei is a cyprinid with an apparently disjunct range: Pahang in Peninsular Malaysia, and the Mae Klong and Chao Phraya in Thailand. It inhabits clear, fast-flowing minor rivers and forest streams, and orange pigmentation in the dorsal and caudal fins helps separate it from congeners. Like others in the genus it is notoriously delicate and difficult to ship, losing scales very easily when removed from the water.

Discherodontus schroederi is a cyprinid native to the Mae Klong and Chao Phraya river basins in Thailand. Said to be the hardiest member of the genus, it is rarely collected for the aquatic trade, presumably because it is the least colourful of the Thai species. Juveniles can be confused with D. ashmeadi, but its dark dorsal blotch fades to a thin distal band with age, and its barbels are noticeably longer than in other members of the genus.

Eirmotus octozona is a small cyprinid with eight dark body bars, known from Johor state in Peninsular Malaysia. The type series came from aquarium fish said to originate at Bueng Boraphet in Thailand, where it has never been recorded since, and if it occurs in Thailand it is probably restricted to the peninsula. It is sold, along with E. insignis, as the 'false eight-banded barb'.

The red-tailed black shark, Epalzeorhynchos bicolor, is a cyprinid native to central and western Thailand, in the Mae Klong and Chao Phraya basins. Declared extinct in 1996, it was found again in 2011 and 2014 and is considered critically endangered, while all fish in the trade are commercially produced. It becomes increasingly territorial as it grows, especially towards similar-looking species, and can live for over 15 years.

The rainbow shark, Epalzeorhynchos frenatum, is a cyprinid reportedly native to Thailand, Laos and Cambodia. Recorded from the Mae Klong, Chao Phraya and Mekong basins, many of its wild populations have dwindled or vanished, and large numbers are farmed for the trade, including an albino and an anerythristic form sometimes misidentified as E. munense. It becomes increasingly territorial as it grows and can live for over 15 years.

The flying fox, Epalzeorhynchos kalopterum, is a cyprinid from southern Thailand, Peninsular Malaysia and the Greater Sunda Islands. Fishes sold as 'false flying fox' or 'Siamese flying fox', such as Garra cambodgiensis and Gyrinocheilus aymonieri, are often confused with it, but it has white-edged red and black fins and two pairs of barbels. It grows increasingly territorial with age and can live for over 15 years.

Epalzeorhynchos munense is a cyprinid from the Mun river and other tributaries of the middle Mekong in Thailand and Laos. It resembles E. bicolor and E. frenatum but has a black head, body and anal fin, red caudal and dorsal fins, and black margins on the pelvic and pectoral fins. A record from the Tonlé Sap system may refer to E. frenatum.

The Mekong flying barb, Esomus longimanus, is a cyprinid from the Mekong basin in Thailand, Laos, Cambodia and Vietnam, and the Tonlé Sap system. It favours shallow, slow-moving and standing waters with dense aquatic vegetation, such as ditches, marshes and rice paddies. Like other Esomus it has greatly enlarged pectoral fins and very long maxillary barbels, and it jumps well enough to escape through the tiniest gaps.

The striped flying barb, Esomus metallicus, is a cyprinid found from the Salween basin in Myanmar east across Thailand to Laos and Cambodia. It is abundant over most of this range and moves into rice paddies and other flooded ground at the onset of the wet season, returning to permanent water when the flooding recedes. Its lateral stripe grows more intense towards the tail and ends at the caudal-fin base.

Folifer brevifilis is a large cyprinid from the Mekong, Salween and Ayeyarwady systems of southern China, Myanmar, Thailand, Laos and Vietnam. It has also been recorded from Hainan and Hong Kong. Growing to 300 mm SL, it is unsuitable for the majority of home aquaria and extremely rare in the ornamental trade. It inhabits flowing middle and lower sections of major rivers and may migrate seasonally to spawn.

The false SAE, Garra cambodgiensis, is a cyprinid from the Mekong, Chao Phraya and Mae Klong basins and northern Peninsular Malaysia. It is still traded as Garra taeniata and is often confused with the Crossocheilus species sold as 'Siamese algae eater'. In this species the dark lateral stripe ends at the caudal peduncle, and a sucker formed by the lower lip is present. It inhabits swiftly-flowing headwaters and tributaries.

Garra fasciacauda is a cyprinid native to the Mekong river system in Thailand, Laos, Vietnam and Cambodia, including the Tonlé Sap basin. It has a black submarginal stripe on both caudal lobes and a plain dorsal fin. It inhabits swiftly-flowing water and migrates seasonally, with many fish moving from the Tonlé Sap system to the Khone Falls in the dry season.

The Burmese red-tailed garra, Garra sp. 'redtail', is a cyprinid from headwaters of the Salween basin around the border between Myanmar and Thailand. A putatively undescribed species, it is often sold as G. sp. 'burmanicus' and first appeared in the trade in 2005. A flexible, proboscis-like rostral process between the eyes becomes erect during territorial conflicts or courtship. It inhabits shady, fast-flowing stretches and riffles.

The 'freshwater' moray eel, Gymnothorax tile, is a moray from coastal regions of the Indo-West Pacific, from eastern India to the Philippines. Although typically sold as a freshwater fish, this is not strictly the case, and the profile treats a marine salt mix as mandatory. It has small pale spots on a darker head and body, where the congener G. polyuranodon has much larger dark spots on a paler background. Highly piscivorous, it is best kept alone in all but the very largest aquaria.

The sucking 'loach', Gyrinocheilus aymonieri, is a stream fish from the Mae Klong, Chao Phraya, Mekong and Dong Nai basins in Indochina. Often sold as a loach, or as the 'Indian' or 'Chinese' algae eater, it is neither a loach nor native to either country. It can live for more than 15 years and is largely unsuitable for the general community aquarium. It is farmed in large numbers, including albino, 'golden', 'piebald' and 'short-bodied' forms.

The spotted hampala barb, Hampala dispar, is a cyprinid endemic to the Mekong basin in northern Laos, Thailand and Cambodia. It needs plenty of space but, at up to 350 mm SL, makes a more suitable aquarium fish than the larger and more commonly traded H. macrolepidota. It has a single dark blotch on the body and less well-defined marginal stripes on the caudal lobes, although juveniles of the two can appear very similar.

Hampala salweenensis is a riverine cyprinid endemic to the Salween basin in northwestern Thailand and Myanmar. It has two roundish dark blotches on each flank, one beneath the dorsal-fin origin and one on the caudal peduncle, and a black marginal band on both caudal-fin lobes. It is poorly known in the aquarium hobby, and the full extent of its distribution within the watershed is unclear.

The kissing gourami, Helostoma temminkii, is an anabantoid from southern Indochina and the Malay Archipelago, and the sole member of its family. The widely traded pinkish-white form is a leucistic variant bred for ornamental purposes, and the 'balloon' variety is intentionally disfigured and much shorter-lived. Its often belligerent behaviour, adult size and life span of over 20 years make it unsuitable for most home aquaria. The 'kissing' appears at least in part related to establishing social dominance.

Hemimyzon nanensis is a balitorid loach known only from the upper Mae Nam Nan river basin, part of the Chao Phraya system in northern Thailand. It was the first member of the genus recorded outside China and Taiwan. At the type locality it was collected in shallow riffles over algae-covered stones, and in the aquarium it needs clean, well-oxygenated water and a biologically mature set-up.

Homaloptera bilineata is a 'lizard' loach from the Sittaung and Salween basins of Myanmar and tributaries of the Mae Klong in western Thailand. Uniquely in the genus, the dark markings running back from the snout form two distinct stripes meeting at the dorsal fin and do not form saddles. An obligate dweller of swift, oxygen-saturated streams, it needs clean, well-oxygenated water and is best kept in a group of six or more.

Homaloptera confuzona is a 'lizard' loach mostly recorded from the Mekong basin in Laos and Cambodia, and from smaller drainages in southern Thailand. It appears in the trade from time to time, though not always identified correctly. It resembles H. orthogoniata and H. parclitella, but its saddle-shaped markings are more irregular, up to four in number, and often restricted to the upper half of the body.

Homaloptera ogilviei is a small 'lizard' loach recorded through much of the Malay Peninsula in both Malaysia and southern Thailand. Quite rare in the trade, it is sometimes imported as bycatch and sold as 'lizard' or 'gecko' loach. Its paired fins are orientated vertically, unlike those of other members of the genus, and in aquaria it perches on the tips of its fins at rest. It favours slower stretches among plants, roots or leaf litter.

Homaloptera parclitella is a 'lizard' loach from Peninsular Malaysia and the Sai Buri, Bang Nara and Kolok river systems of southern Thailand. It was previously considered a form of H. orthogoniata and may be seen identified as such online and in print. It always has two large, saddle-shaped markings on the back, where H. orthogoniata has three, and it lives in swift, clear, oxygen-saturated streams.

Homalopteroides modestus is a small hillstream loach from the Salween, Mae Klong and Tenasserim rivers of southern Myanmar and western Thailand. Randall and Page (2012) redescribed it from Mae Klong specimens that had previously been identified as the congener H. smithi. A specialised micropredator of swift, clear, oxygen-saturated streams, it needs clean, well-oxygenated water and regular meals of live or frozen food.

Homalopteroides smithi is a hillstream loach from Thailand, Peninsular Malaysia and parts of the Mekong basin in Laos, Cambodia and Vietnam. Perhaps the best-known member of the genus, it is relatively common in the aquarium hobby, and Rainboth (1996) considered it 'probably the commonest member of the genus in the Mekong'. An obligate dweller of swiftly-flowing streams and headwaters, it needs clean, well-oxygenated water.

Homalopteroides tweediei is a small hillstream loach from Peninsular Malaysia, the Mekong system and West Kalimantan in Indonesian Borneo. It is often confused with the congener H. smithi. Rainboth (1996) found it less likely to occur in riffles or runs than other members of the genus, and it shows a preference for moderately-flowing stretches of clear, oxygen-rich streams among patches of live or dead vegetation.

Hypsibarbus lagleri is a large cyprinid endemic to the middle Mekong basin in Laos, eastern Thailand and Cambodia. It migrates seasonally, living in larger river channels in the dry season and moving into smaller tributaries and flooded forests in the wetter months. Growing to 350 mm, it is a valued food fish, and like most of its congeners is thought to be in decline because of the damming of rivers and agriculture.

Hypsibarbus vernayi is a cyprinid widespread in mainland Southeast Asia, from the Mekong basin in southern China to northern Peninsular Malaysia. Very similar to H. wetmorei, it has yellow pectoral, pelvic and anal fins (orange to red in H. wetmorei), so yellow-finned fish sold as H. wetmorei or 'lemon fin barb' appear likely to be this species. It prefers flowing water with abundant riparian vegetation and migrates seasonally.

Hypsibarbus wetmorei is a cyprinid widespread in mainland Southeast Asia, from the lower Mekong basin south to the Pahang River in Malaysia. Its orange to red pectoral, pelvic and anal fins separate it from the very similar H. vernayi (yellow), and yellow-finned fish traded as H. wetmorei or 'lemon fin barb' appear likely to be that species. It prefers flowing water with abundant riparian vegetation and grows to 250 mm.

Indostomus crocodilus is a tiny indostomid, 25 to 30 mm long, from southern Thailand and Kelantan state in northeastern Peninsular Malaysia. Its type series came from a blackwater stream in peat swamp forest, among submerged roots and leaf litter in slow-moving or standing water. A poor competitor, it is best kept alone or with similarly-sized, placid species, and males have dark brown to black bars in the dorsal and anal fins.

The fire bar 'danio', Inlecypris maetaengensis, is a small cyprinid endemic to the Mae Nam Ping drainage in northern Thailand. Also traded as 'tiger danio', it is most easily confused with 'I.' shanensis and Devario interruptus, and has a complete lateral line with 31 to 35 pored scales and a P stripe of contiguous blotches. It inhabits small, clear, moderate-to-swiftly-flowing streams with no aquatic vegetation.

Kryptopterus bicirrhis is a silurid catfish from much of Southeast Asia, including the Mekong and Chao Phraya and the Greater Sunda Islands. Uncommon in the aquarium trade, its name was widely misapplied to K. vitreolus in older literature, but the two are easily told apart because K. bicirrhis does not have a transparent body in life. It tends to form schools, so four or more should be kept.

Kryptopterus geminus is a silurid catfish from the lower and middle Mekong in Thailand, Laos, Cambodia and Vietnam, and the lower Chao Phraya. Wild populations were formerly considered K. cryptopterus, and it is likely to be traded as that very similar species. It differs in having a narrower head, a longer snout and anal fin and more laterally-placed eyes, and inhabits flowing rivers and larger streams with turbid water.

Kryptopterus limpok is a silurid catfish widely distributed through Southeast Asia, including the Mekong and the Greater Sunda Islands. It can be told from its congeners by an extremely long mental barbel extending beyond the tip of the pectoral fin. It inhabits flowing rivers and larger streams with turbid water, grows to 260 mm and is almost unheard of in the ornamental trade.

The striped glass catfish, Kryptopterus macrocephalus, is a silurid catfish from Thailand, Malaysia, Singapore and the Greater Sunda Islands. A stenotypic inhabitant of peat swamp forests and associated blackwater streams, it is also known as the false, mottled or tawny glass catfish. Striped and mottled colour forms exist that may or may not be conspecific, and the similar K. piperatus has a pale brown body with scattered dark spots.

The glass catfish, Kryptopterus vitreolus, is a transparent silurid catfish from coastal river basins of peninsular and southeastern Thailand. Available in the trade for decades, it was widely misidentified as K. bicirrhis or K. minor until its description in 2013, so older literature uses those names. It is also sold as the 'Asian glass catfish', 'ghost catfish' or 'phantom catfish'. Its status in the wild requires investigation since it is collected intensively and has a restricted range.

Labiobarbus leptocheilus is a large cyprinid widespread in Southeast Asia, from the Mekong and Salween to the Greater Sunda Islands. Different populations vary somewhat in appearance, and it may turn out to represent a group of closely-related species. The Cambodian Mekong population has been considered a distinct species, Labiobarbus lineatus, and that name is widely used in the ornamental trade although it is currently a synonym. It grows to 260 mm SL and needs spotless, well-oxygenated water.

The flying minnow, Laubuka caeruleostigmata, is a cyprinid from the Mekong system in Laos, Thailand and Cambodia, and the Chao Phraya and Mae Klong. Also known as 'leaping barb', it was once quite common in the ornamental trade and has apparently become scarce in the wild. It schools near the surface in main river channels, has a bright blue spot on top of the head, and is an accomplished jumper that needs a tightly-fitting cover.

Laubuka siamensis is a cyprinid from the Mekong, the Chao Phraya and Mae Klong in Thailand, and smaller drainages south to Peninsular Malaysia. Long considered synonymous with L. laubuca, it seems likely to be the species behind many of the fish entering the trade under that name. A conspicuous dark stripe, iridescent blue in life, runs uninterrupted along the rear of the body to an oval blotch on the caudal peduncle. It swims in groups at or just below the surface and is an accomplished jumper.

Lepidocephalichthys berdmorei is a cobitid loach found across Myanmar, Thailand, Laos, north-eastern India and Bangladesh. One of the most frequently-traded members of the genus, it is an excellent choice for those new to keeping loaches. Unlike most congeners it shows a preference for headwaters and streams with clear, flowing water, and its larger adult size separates it from the similar L. thermalis.

Lepidocephalichthys furcatus is a small cobitid loach from Peninsular Malaysia, southern Thailand and North Sumatra, Indonesia. Not traded often, it turns up occasionally as bycatch among shipments of other species. It is told apart from congeners most easily by the prominent, roughly semi-circular lamina circularis in males, a feature unique within the genus, and it has a forked caudal fin.

Lepidocephalichthys hasselti is a cobitid loach described from Java and recorded from Myanmar to Vietnam, Peninsular Malaysia, Sumatra and Borneo. Its wide distribution makes it relatively common in the aquarium hobby. Colour and pattern vary with locality and have led to problems with identification, and the flanks usually show a row of dark blotches or a solid stripe with a light, unpigmented stripe above.

Lepidocephalichthys kranos is a cobitid loach from the Chao Phraya system in Thailand and the Mekong in Thailand, Laos and Vietnam. Some private collectors have kept it. Its colour pattern tends to form a mosaic, unlike the irregular spotting of most congeners, and the body deepens steeply behind the snout to give a 'hunched' appearance. It can often be found living with L. hasselti.

Lepidocephalichthys micropogon is a cobitid loach from Myanmar, western Thailand, Bangladesh and Assam, India. Known from the Salween, Sittaung, Irrawaddy and Brahmaputra drainages and occasionally exported as bycatch, it grows to 55 mm SL and has a strongly forked caudal fin with broad, dark V-shaped bars. Kottelat (2012) treats L. manipurensis as a synonym, though Havird and Page (2010) list the two separately.

Lepidocephalichthys zeppelini is a tiny cobitid loach from the Mekong system in Thailand and Vietnam and the Chao Phraya drainage in central Thailand. Adults reach only 25.8 mm SL, and the lamina circularis of mature males forms a large, finely serrated flange. Many adults at the type locality were collected from remnant ephemeral pools in otherwise dry agricultural land.

Lepidocephalus macrochir is a cobitid loach described from Sumatra and since recorded from Thailand, Peninsular Malaysia, Java and Borneo. It is traded sporadically as the 'pinky loach', 'deep water kuhli loach' and 'Borneo high body cave loach'. Although sometimes said to be a cave loach, Thai collectors report it from deep water, and in aquaria it spends a lot of time buried in soft substrates.

Lobocheilos melanotaenia is a grazing cyprinid from the Mekong in Laos, Thailand, Cambodia and Vietnam, plus the Dong Nai, Chao Phraya and Mae Klong. One of the most abundant species in the seasonal cyprinid migrations of the mainstream Mekong, it is available on a sporadic basis. It is told from L. rhabdoura by its deeper body, narrower mouth and a dark area in the dorsal-fin. It can be aggressive at feeding times and is not particularly tolerant of conspecifics.

Lobocheilos rhabdoura is a grazing cyprinid from Indochina, found in the Mekong, Chao Phraya and Mae Klong systems and south to Peninsular Malaysia. One of the most abundant species in the seasonal cyprinid migrations of the mainstream Mekong, it is available on a sporadic basis. It differs from L. melanotaenia in its shallower body, wider mouth and larger snout tubercules. It can be aggressive at feeding times and is not particularly tolerant of conspecifics.

Luciosoma bleekeri is a slender, pike-like cyprinid from the Mekong in Laos, Thailand, Cambodia and Vietnam, and from central and western Thailand. Subadults are traded regularly as 'apollo shark' or 'shark minnow' and it is frequently confused with L. setigerum, which has a series of black spots on the lateral line scales that this species lacks. It needs the largest private aquaria, and feeds mainly on terrestrial insects taken at the surface.

The apollo shark, Luciosoma setigerum, is a slender cyprinid found across much of Southeast Asia, from the Mekong basin to Borneo, Sumatra and Java. Subadults are traded regularly and are frequently confused with L. bleekeri, which lacks the series of black spots on the lateral line scales. A similar fish of unknown origin with no stripe on the front of the body is also common in the trade, listed as L. cf. setigerum. It needs the largest private aquaria.

The fire eel, Mastacembelus erythrotaenia, is a spiny eel recorded from Laos, Vietnam, Cambodia, Thailand, Malaysia and Indonesia. It usually inhabits sluggish lowland waters including floodplains and slow-moving rivers, and is also a food fish in its native countries. In the aquarium it hides away during the day and often buries itself, so it needs a sand substrate, plenty of cover and a close-fitting hood.

Microdevario kubotai is a miniature cyprinid from peninsular Thailand and the Salween drainage in southern Myanmar. Relatively common in the ornamental trade, it is sold under names including 'green neon rasbora' and 'yellow neon rasbora'. It apparently inhabits calm to moderately-flowing, well-oxygenated headwaters and minor tributaries. In nature it typically occurs in groups of 20-50, and at least 8-10 are recommended.

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 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 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.