Peninsular Malaysia

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 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.

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 silver shark, Balantiocheilos melanopterus, is a large cyprinid from Borneo, Sumatra and possibly Peninsular Malaysia. Also sold as the 'Bala shark', it is among the most commonly encountered ornamental fishes, yet it reaches 300 to 350 mm SL and long-term care is beyond most hobbyists. Wild populations have dwindled or vanished, it has been listed as Endangered by the IUCN since 1996, and fish on sale are almost certainly all commercially bred. It does not occur in Indochina.

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 banksi is a cyprinid from Peninsular Malaysia, Singapore and western Borneo, plus the Anambas and Natuna islands of Indonesia. It is tentatively considered distinct from the closely related B. binotatus, differing in a dark, wedge-shaped marking below the dorsal fin in place of a midlateral spot, though the two may be colour forms of a single species. Occasionally exported as bycatch, it lives in habitats from fast hill streams to canals and floodplain ponds.

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 clown barb, Barbodes dunckeri, is a cyprinid from Peninsular Malaysia, described from Singapore, where it may now be extirpated. It has been widely misidentified as B. everetti, a distinct species from Borneo, and appears under that name in most aquarium literature. B. dunckeri has much larger dark body markings, no blotch at the rear of the dorsal-fin base and 4½ scales above the lateral line. Fish entering the ornamental trade appear to be farm-raised.

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.

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 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.

Belodontichthys dinema is a large, open-water predatory catfish from the Malay Peninsula, Sumatra and Borneo that reaches 100 cm TL in the wild. It eats only fish and needs a very large aquarium without tankmates small enough to swallow. Fish exported from Thailand or elsewhere in Indochina under this name are likely to be B. truncatus, the species found in the Mekong and Chao Phraya basins.

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 slender betta, Betta bellica, is a bubble-nesting labyrinth fish from Peninsular Malaysia and northeastern Sumatra, Indonesia. It lends its name to the B. bellica group of long, slender fishes with iridescent green markings on each scale. Most often found in peat swamp forests and blackwater streams, it feeds almost entirely on insects and is a prodigious jumper, seen leaping to take prey from overhanging leaves. Populations are often labelled by locality to preserve pure bloodlines.

The scarlet betta, Betta coccina, is a small bubble-nesting labyrinth fish from Jambi and Riau provinces in Sumatra and Johor in Peninsular Malaysia. It lends its name to the B. coccina group and is a stenotopic inhabitant of peat swamp forests and associated streams. Males carry an iridescent green lateral blotch that females lack, and populations are often labelled by locality, such as Jambi, Riau or Johor, to preserve pure bloodlines.

Betta hipposideros is a paternal mouthbrooding labyrinth fish from peat swamps in western Peninsular Malaysia and eastern Sumatra, Indonesia. A member of the B. waseri group, it is most easily told from its relatives by a black horse-shoe shaped marking on the throat. An obligate inhabitant of peat swamps and blackwater streams, where the pH can be as low as 3.0 or 4.0, it may have to survive for several weeks in moist leaf litter at certain times of year.

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 persephone is a small bubble-nesting labyrinth fish that appears to be endemic to southwestern Johor state, Peninsular Malaysia. A blackish member of the mostly red B. coccina group, it is most similar to B. miniopinna but has a deeper body and blackish to dull reddish pelvic fins. It inhabits peat swamp forests and associated streams, where the pH can be as low as 3.0 or 4.0.

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 pugnax is a paternal mouthbrooding labyrinth fish from much of Peninsular Malaysia and Singapore, described from Penang. It lends its name to the B. pugnax complex. Populations inhabit shallow, flowing clear-water hill streams as well as stiller forest swamps. It is not among the more aggressive members of the genus and can be maintained in a pair or group.

Betta pulchra is a mouthbrooding labyrinth fish from southwestern Johor in southern Peninsular Malaysia. It is restricted to remnant blackwater habitats in heavily-disturbed former peat swamp forest cleared for oil palm, pineapple and rubber plantations, where it lives among the overhanging marginal vegetation of irrigation canals at a pH of 3.9 to 4.2. A member of the B. pugnax complex, it has a chin bar, transverse bars in the caudal fin and iridescent green scales on the opercle.

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.

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.

Brevibora cheeya is a small cyprinid from Peninsular Malaysia, Sumatra and the island of Bangka. The type locality is a slow-flowing, acidic stream in coastal heath forest over sand and peat. Very rare in the trade, it is normally imported only as bycatch among other fishes. A complete lateral line, more scales in the lateral row and a larger adult size separate it from the better-known B. dorsiocellata.

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 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.

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.

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 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 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.

Normally traded as the 'pentazona' barb, Desmopuntius hexazona is a cyprinid from southern Borneo, eastern Sumatra, Singapore and the Malay Peninsula. It is almost identical to D. pentazona, which has a small dark marking at the rear of the dorsal-fin base that D. hexazona lacks. Older literature may label it 'Puntius johorensis'. In Singapore it is considered highly endangered and is restricted to the Central Catchment nature reserve.

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.

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 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.

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 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.

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.

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.

Gymnochanda filamentosa is a small glassfish known from Johor in southern Peninsular Malaysia and the Kapuas system in West Kalimantan, Borneo. Males carry filamentous dorsal and anal-fin rays, and the body is transparent to translucent yellowish-brown in life. It occurs in swampy, acidic waters over silt and peat, and has appeared in the ornamental trade but is evidently delicate and recommended only to experienced aquarists.

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 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.

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 nebulosus is a small hillstream loach described from the Sok River in northern Peninsular Malaysia and since recorded from Borneo. Poorly known in the aquarium hobby, it may never have been exported for the ornamental trade. Its eyes sit in a comparatively raised position on the head, as in H. tweediei, but it has more lateral line scales. Little is known of its habitat, which is presumed to be swiftly-flowing streams and headwaters.

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.

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.

Kottelatlimia pristes is a small cobitid loach from Peninsular Malaysia, Sumatra and Borneo, the most widely-distributed member of its genus. It inhabits small, slow-moving forest streams and peat swamps with tannin-stained water, often in piles of leaf litter. It turns up occasionally in the trade, sometimes as bycatch among other species and under names such as 'Sumatran mini royal loach' or Cobitis cf. sumatranus.

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.

The blue sheatfish, Kryptopterus cryptopterus, is a silurid catfish from the Malay Peninsula, Singapore, Sumatra, Borneo and Java. It inhabits flowing rivers and larger streams with turbid water, and is sometimes traded as 'smokey glass catfish'. Populations from Thailand, Cambodia, Laos and Vietnam once considered conspecific are now referred to K. geminus, its closest relative, from which it differs in having a wider head and a shorter snout and anal fin.

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.

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.

Labiobarbus ocellatus is a cyprinid from Peninsular Malaysia, Sumatra and Borneo, with a black spot on the shoulder and one on the caudal peduncle. It is occasionally available in the ornamental trade, typically under a name such as 'Bornean eye-spot silver shark' or the invalid scientific name Cirrhinus chinensis. A pelagic species of rivers and some lakes, it moves into seasonally inundated floodplains and forest during the wet season, and grows to 180 mm SL.

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 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 tomaculum is a small cobitid loach from Peninsular Malaysia, with a single tentative record from Lampung Province, Sumatra. It inhabits shallow, slow-moving streams, swamps, oxbows and backwaters over mud, silt or peat. Occasionally available as bycatch, it has a reddish brown body with thin dark bars across the back, and where it lives with L. hasselti identification can be difficult.

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 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.

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.

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.

Nemacheilus masyae is a nemacheilid loach from Thailand and Peninsular Malaysia. Its flanks carry 14-18 short dark bars and its back 12-17 saddles. It occurs in both small blackwater forest streams and turbid main river channels. It is very similar to N. pallidus but has a more slender body, and its dark bars and saddles are wider than the light interspaces between them.

Nemacheilus selangoricus is a nemacheilid loach ranging from southern Thailand through Peninsular Malaysia and Singapore to western Borneo and Sumatra. It is most common in shallow, flowing forest streams over sand, gravel and detritus. It belongs to the N. selangoricus group and is most similar to N. spiniferus, from which it differs in its 8-12 very regular dark bars on the flanks.

Neohomaloptera johorensis is a tiny balitorid loach from Peninsular Malaysia, found mainly in peat swamps and associated blackwater streams. Its small adult size and orange to reddish-brown colour make it difficult to confuse with any other balitorid. The water in its habitat is stained brown, with negligible mineral content and pH as low as 3.0 or 4.0. It needs well-oxygenated water free of organic pollutants.

The Javanese ricefish, Oryzias javanicus, ranges through Peninsular Thailand, Malaysia, Singapore and Indonesia as far east as Lombok and Sulawesi. Typically found in coastal, normally brackish, streams, pools and mangrove swamps, it tolerates a wide salinity range and has also been recorded in fresh water. It is exported on occasion and sometimes referred to as the 'blue-eyed ricefish'.

Traded as 'eel loach', Pangio anguillaris is a cobitid loach from Borneo, Sumatra, Peninsular Malaysia and the Chao Phraya and Mekong basins. It has an extremely elongated, worm-like body with 69-71 vertebrae and no nasal barbels, and is most commonly available as bycatch among shipments of other fishes. The species as currently recognised appears to represent a complex of closely-related taxa.

Pangio cuneovirgata is a small kuhli loach from southern Thailand, Peninsular Malaysia, Sumatra and western Java, found in forest streams and swamps. It has 7-13 dark saddles on the upper half of the body and looks most like P. malayana, but has nasal barbels and a truncate caudal-fin. It is infrequently encountered in the trade, most often as bycatch among shipments of similar-looking congeners.

Traded as 'eel loach', Pangio doriae is a worm-like cobitid loach from Sarawak in Borneo and from Peninsular Malaysia. Some authors have suggested it is synonymous with P. anguillaris, but it can be told apart by a pair of prominent nasal barbels. The Sumatran population once identified as this species was described as P. bitaimac in 2009. It is most commonly available as bycatch among shipments of other fishes.

Pangio filinaris is a plain-bodied kuhli loach known only from Pahang and Terengganu states in Peninsular Malaysia. It has been confused with P. mariarum, which shares its plain patterning and nasal barbels, and has also been referred to by the invented name P. 'mariae'. It is sometimes exported for the aquarium trade, normally as by-catch among shipments of other species.

Pangio malayana is a barred kuhli loach from Peninsular Malaysia, the Batang Hari drainage in Sumatra and the Kapuas system in Indonesian Borneo. It has 10-16 dark saddles on the upper half of the body and a black bar at the base of the caudal-fin, and looks most similar to P. cuneovirgata, which has a truncate caudal-fin. It is most often encountered as bycatch among shipments of similar-looking congeners.

Pangio piperata is a slender kuhli loach from Peninsular Malaysia, Riau Province in Sumatra and the Rajang river drainage in Sarawak. Its yellowish-brown body is peppered with small dark spots forming a rough stripe along the lateral line. Some populations of the variable P. shelfordii look similar and the two often occur together, but P. piperata is generally plainer and has fewer vertebrae. It is exported occasionally, most often as bycatch among congeners.

Usually sold as the 'kuhli' loach, Pangio semicincta is a cobitid loach from Peninsular Malaysia, Sumatra and Borneo. It lives in shallow forest streams and swamps, often in black water, and is typically abundant in leaf litter. P. kuhlii itself is currently considered endemic to Java and has possibly never been seen in aquaria, so the common aquarium 'kuhli' is more likely to be this species or an unidentified relative.

Pangio shelfordii is a variably patterned kuhli loach from Peninsular Malaysia, Singapore, Sumatra and Borneo. Its patterning varies within and between populations, and as currently understood the species represents an assemblage containing a number of unidentified taxa. Some Sumatran and Bornean populations resemble P. piperata, which often occurs alongside it. It is exported occasionally, often as bycatch among shipments of congeners.

Paracanthocobitis zonalternans is a nemacheilid loach ranging from Manipur in India through Myanmar into western and peninsular Thailand. Several species are thought to be confused under the name, and Singer and Page (2015) consider it likely to be a species complex. Among the more peaceful members of the genus, it does best in a mixed-sex group of at least half a dozen, and it has been bred in aquaria, first by UK aquarist Mick Wright.

Parosphromenus harveyi is a liquorice gourami from the north Selangor peat swamp forest in Peninsular Malaysia, with one population in Perak. Its type description was a hobbyist-magazine announcement with limited diagnostic information. Males have plain blue pelvic fins with a filamentous tip longer than the fin itself and a notably wide black subdistal band in the caudal fin. Much of its habitat has been lost and it is considered in danger of extinction.

Parosphromenus nagyi is a liquorice gourami known only from part of Peninsular Malaysia's eastern coast, between Cherating and Nenasi. Males have iridescent emerald green pelvic fins with a very short filamentous tip, and the light band in the caudal fin differs slightly between populations. Much of its habitat has been lost to deforestation, and in most places it now survives only in remnants such as irrigation ditches and roadside canals.

Parosphromenus tweediei is a liquorice gourami restricted to a handful of localities in western Johor state, Peninsular Malaysia. Known in the hobby since the mid-twentieth century, it has almost always been identified as P. deissneri and appears as such in most aquarium literature. Males have a black subdistal band in the unpaired fins with a broad, vivid red band inside it. It has been extirpated from Malacca and is considered in grave danger of extinction.

Pseudohomaloptera leonardi is a 'lizard' loach ranging through Peninsular Malaysia and north into Thailand as far as the Tapi river drainage. Seriously Fish referred to it as Homaloptera sp. 'H01' before its identity was established. It is very similar to P. sexmaculata, and both are sometimes misidentified as H. yunnanensis. Naturally reclusive, it needs clean, fast-flowing, well-oxygenated water and a group of four or more.

Puntigrus partipentazona is a small cyprinid recorded from numerous river basins in Vietnam, Cambodia, Laos, Thailand and Peninsular Malaysia. It is easily told from congeners because the dark blotch on its dorsal fin extends onto the body. Typically found in heavily vegetated parts of rivers and sluggish streams, it is generally peaceful, though rival males continually battle for position within the group.

The lined barb, 'Puntius' lineatus, is a laterally-striped cyprinid from Peninsular Malaysia, Sumatra and Borneo, found mostly in peat swamps. It is most often confused with 'P.' johorensis, the two being the most common of the striped species in the trade, but it has no more than one pair of barbels, lacks vertical bars as a juvenile and grows smaller. Its habitats include black water streams stained brown with humic acids, with pH as low as 3.0 or 4.0.

The silver rasbora, Rasbora argyrotaenia, is a cyprinid from Peninsular Malaysia, Singapore, Sumatra, Java, Borneo and the Palawan islands. One of the larger rasboras at up to 140 mm TL, it is a plain, silvery fish with a faint dark stripe, and fish pictured under this name with a bold black stripe are probably a regional variant of R. daniconius. A DNA barcode study found two mitochondrial lineages under the name, and the species as currently recognised is likely to be split.

Rasbora dusonensis is a cyprinid from Sumatra, Peninsular Malaysia and Borneo, found in larger river channels and peat swamp blackwaters. Its identity was unclear for decades before its redescription by Ng and Kottelat (2013). It is very similar to R. tornieri, which shares the Musi river with it, but has a bright yellow caudal fin with a broad dark margin, against carmine red in R. tornieri. One specimen measured 162 mm SL, although 95 to 105 mm is a more commonly reported adult size.

Rasbora tornieri is a cyprinid from Sumatra, Borneo, Peninsular Malaysia and the Mekong drainage in Cambodia. Its identity was unclear for decades before its redescription by Ng and Kottelat (2013). It is very similar to R. dusonensis, which shares the Musi river with it, but its caudal fin is carmine red, against bright yellow in R. dusonensis. It lives in flowing streams and peat swamp blackwaters alike.

Schistura robertsi is a small nemacheilid loach from the western slope of the Malay Peninsula in southern Thailand and Malaysia. It inhabits shallow, narrow branches of streams over sand, gravel or stone, and adults carry 8-10 regular dark body bars wider than the pale interspaces. It may have been exported alongside similar-looking relatives such as S. cf. balteata, and like many fishes from running water it is intolerant of organic pollutants.

The chocolate gourami, Sphaerichthys osphromenoides, is a small gourami from Peninsular Malaysia, Sumatra and Borneo. By far the best known member of the genus, it mostly inhabits peat swamps and black water streams where the pH can drop to 3.0 or 4.0. A maternal mouthbrooder, it is slow-moving and easily outcompeted for food by more boisterous tankmates.

Systomus orphoides is a large cyprinid ranging from Myanmar to Vietnam and south through Peninsular Malaysia to Borneo, Sumatra and Java. It mostly inhabits flowing tributaries and large streams, moving onto inundated farmland and forest in the wet season to feed and spawn. Not often available in the trade and usually seen as bycatch, it grows to 250 mm SL, is quite boisterous, and needs more-or-less spotless water.

The croaking gourami, Trichopsis vittata, is a labyrinth fish found through much of Indochina, Peninsular Malaysia and Singapore. The largest of its genus, it produces audible sounds with a specialised pectoral mechanism unique within the Osphronemidae. Wild populations vary in colour pattern, and records from Borneo, Sumatra and Java might refer to a distinct species.

Trigonopoma gracile is a small rasbora from the blackwater peat swamps of Peninsular Malaysia, Borneo and Sumatra. Its colour forms vary with collection locality. The name Rasbora agilis has been applied to it since a 1971 book pictured it under that name, but R. agilis is a junior synonym of T. pauciperforatum, the fish it is said to resemble.

The glowlight rasbora, Trigonopoma pauciperforatum, is a small cyprinid from Peninsular Malaysia, Singapore, Borneo and Sumatra. Also sold as the 'redline' rasbora, its lateral stripe varies from deep orange to golden with locality, diet, condition and mood. It inhabits blackwater streams associated with peat swamps, where the pH can drop as low as 3.0 or 4.0, and the name R. agilis is a junior synonym of it.

The harlequin, Trigonostigma heteromorpha, is a small cyprinid from southern Thailand, Peninsular Malaysia, Singapore and Sumatra. First exported for aquaria in the early 1900s, it is now mass-produced, and farmed fish lack much of the colour of wild ones. The dark triangular body marking sets it apart from T. espei and T. hengeli, and two divergent lineages found in aquarium stock suggest the species as currently recognised may contain more than one taxon.

The fork-tailed loach, Vaillantella maassi, is a loach from Sumatra, Borneo, Peninsular Malaysia and southern Thailand. Traded as 'chocolate scissor-tailed loach' and 'dragon loach' among other names, it has a bluish-brown body with an orange to yellow dorsal stripe. Rarely traded in numbers, it is among the more reclusive loaches and can be aggressive with its own kind and other fishes.

Xenentodon canciloides is a freshwater needlefish from Borneo, Sumatra, Peninsular Malaysia and Thailand, and is considered to occur in the Mekong. Rarely seen in the ornamental trade, it is far less common there than its congener X. cancila, from which it differs in its slender, delicate jaws and smaller size, not exceeding 30 cm TL. A near-exclusive inhabitant of the upper water column, it is surprisingly peaceful with anything too large to swallow and is best kept in numbers of four or more.

The freshwater toadfish, Allenbatrachus grunniens, is a euryhaline toadfish from the Ganges delta in India and Bangladesh east to the Philippines. It is relatively common in the hobby and, contrary to popular belief, not venomous, but its dorsal and opercular spines can pierce the skin, so it needs netting with extreme caution. It rarely does well when kept in freshwater for prolonged periods.

The giant snakehead, Channa micropeltes, is a predatory fish from Southeast Asia that grows to well over a metre. Juveniles are sold as 'red' or 'redline' snakehead, but it is suitable only for public installations or the very largest private aquaria. Unlike most Channa species it is pelagic and needs plenty of room to swim, and adults become aggressive at sexual maturity.

The giant featherback, Chitala lopis, is a notopterid accepted to range from the Mekong basin to Peninsular Malaysia, Sumatra, Borneo and Java. That range appears to require confirmation: it may already be extinct on Java, and the species may comprise several closely-related taxa. Older juveniles and adults lack the dark body markings of other Chitala and have a more pronounced jaw, and at up to 1500 mm SL it is suitable only for public installations or the very largest private aquaria.

Crossocheilus cobitis is a cyprinid ranging from the Mekong drainage in Laos, Vietnam and Thailand south to Sumatra, Borneo and Java. Primarily a lowland species, it lives in the turbid lower reaches of rivers over mud, close to submerged logs and similar objects. Given its wide range it has probably reached the trade as the invalid 'Crossocheilus siamensis', and it is likely to represent a group of similar-looking, closely related species.

Cyclocheilos enoplos is a large cyprinid from the Mekong region and Thailand south through Peninsular Malaysia to Borneo, Sumatra and Java. Growing to around 750 mm SL, it is clearly unsuitable for aquaria and scarce to non-existent in the ornamental trade. In the Mekong it makes long seasonal migrations, and adults move upstream above Khone Falls in what appear to be spawning migrations.

The Indonesian tiger perch, Datnioides microlepis, is a large tiger perch from Peninsular Malaysia, Sumatra and Indonesian Borneo. It has 6 to 7 wide dark bars and small body scales, lives only in large, deep lowland rivers, and grows to 500 mm SL. Juveniles may form groups, but adults are not gregarious and respond aggressively to conspecifics and similarly-shaped fishes.

The hampala barb, Hampala macrolepidota, is a cyprinid ranging from Myanmar through Thailand to the Mekong, and south to Borneo, Sumatra and Java. Also known as 'jungle perch' or 'sidebar barb', it can grow to over 2 feet and 5 kg and is a powerful, pelagic predator and not an aquarium subject in all but the most extreme circumstances. Prized as a food and sport fish, it has been introduced to numerous water bodies.

The crystal-eyed catfish, Hemibagrus wyckii, is a bagrid with an enormous distribution across central Indochina and western Indonesia. Juveniles are sometimes available in the aquarium trade, but buying them is strongly discouraged: it reaches 710 mm SL, is aggressively territorial and can live for several decades. Despite the common name, the blue eye is not given as a distinguishing character in any diagnosis we've seen.

The goldfin tinfoil barb, Hypsibarbus malcolmi, is a large cyprinid from Thailand, Laos, Cambodia and Peninsular Malaysia. It occurs throughout the Mekong system and in the Chao Phraya and Maeklong drainages, and in the Mekong migrates seasonally between larger river channels and flooded forests. Reaching 400 to 500 mm, it is suitable only for public aquaria or the very largest private set-ups.

The black shark, Labeo chrysophekadion, is a large cyprinid from Southeast Asia, including the Mekong, Chao Phraya and the Greater Sunda Islands. Also known as the black sharkminnow, it reaches 600 mm and is aggressively territorial towards conspecifics and similarly-shaped fishes. It continues to be sold despite its patent unsuitability for the home aquarium, and an albino form has been selectively bred for the trade.

The mad barb, Leptobarbus hoevenii, is a large pelagic cyprinid apparently native to Peninsular Malaysia, Borneo, Sumatra and Java. A popular sport fish growing to 800 to 1000 mm, it is wholly unsuitable for private aquaria but is readily available at 100 to 150 mm. The congener L. rubripinna was referred to as L. hoevenii for decades and both are traded under the same name. L. hoevenii lacks the broad dark midlateral stripe and has dark grey pelvic and anal fins.

The giant sword minnow, Macrochirichthys macrochirus, is a large pelagic cyprinid widespread in Southeast Asia, from the Mekong to Borneo and Sumatra. Growing to 600 to 800 mm and becoming increasingly piscivorous as it grows, it is unsuitable for the majority of private aquaria, although juveniles are traded on occasion. It is thought to have been extirpated from the Chao Phraya, Mae Klong, Lake Songkhla and Java, and the Mekong populations have been drastically reduced.

The bronze featherback, Notopterus notopterus, is an air-breathing notopterid from the Indian subcontinent and Southeast Asia. Also called 'Asian knifefish' or 'ghost knifefish' in the trade, it grows to 600 mm and arguably has no place in the ornamental hobby given its adult size and specialised requirements. The single species in Notopterus is likely to represent a complex of closely-related species.

Phalacronotus apogon is a large silurid catfish from much of Southeast Asia, including Thailand, the Mekong basin and the Greater Sunda Islands. It reaches 700 mm and arguably should not be considered a home aquarium subject at all, but juveniles are sometimes sold as 'blue neon sheatfish' or 'metallic cheatfish' without adequate information on long-term care. It is an important food fish across much of its native range.

The Asian arowana, Scleropages formosus, is an osteoglossid from the Mekong system, eastern Thailand, Peninsular Malaysia, Sumatra and Borneo. Highly valued in the aquarium trade since the 1970s and listed on Appendix I of CITES since 1975, it is now extirpated across much of its range. It occurs in several colour forms, such as the 'super red' of the upper Kapuas, and three were described as species in 2003, though the majority view treats all of them as S. formosus pending review.

Labiobarbus fasciatus is a labeonin cyprinid from the Pahang River system in Peninsular Malaysia and the islands of Sumatra and Borneo. It has a red caudal fin with a thin dark stripe along each lobe, and longitudinal stripes formed by spots on the scales. Like other Labiobarbus it has two pairs of well-developed barbels and an extremely long dorsal fin, and the genus was known as Dangila for over 100 years.

Bagarius bagarius is a sisorid catfish with a wide but disjointed recorded range, from the Indus in Pakistan east to the Mekong and Malay Peninsula. Its identity is confused: the name has been widely applied to a small fish said to reach only 200 mm SL, but it may be the only Bagarius in the Indian subcontinent, in which case it can reach 2 metres. It is mostly collected from fast, turbulent rapids in larger rivers, where it shelters among boulders, and is best kept alone.