Labyrinth Fishes

The honey gourami, Trichogaster chuna, is a labyrinth fish from the Ganges and Brahmaputra systems of India and Bangladesh, with records from Nepal. Virtually all fish on sale are commercially produced, and ornamental strains such as 'red', 'sunset' and 'golden' exist. Slow-moving and easily outcompeted, it needs peaceful tankmates and does best in a group of four to six.

The thick-lipped gourami, Trichogaster labiosa, is a labyrinth fish known only from southern Myanmar, found in shady, weedy rivers and ponds. Easy to keep and peaceful, it is one of the best gouramis for a community tank. A gold or 'sunset' strain has been selectively bred for the trade. It should not be kept with the banded gourami because the two can hybridise freely.

The pearl gourami, Trichopodus leerii, is a labyrinth fish from Thailand, Malaysia, Borneo and Sumatra, where it inhabits lowland swamps. One of the most peaceful gouramis, it is hardy and fairly long-lived, surviving 8 years or more in the aquarium. Wild fish are rare in the hobby, and most on sale are mass-produced in the Far East and Eastern Europe.

The sparkling gourami, Trichopsis pumila, is a small labyrinth fish from the lower Mekong basin and central and southern Thailand. Also known as the pygmy gourami, it has a solid dark midlateral stripe topped by a row of dark blotches, which with its small size separates it from T. schalleri. Both sexes produce audible 'croaking' sounds with a specialised pectoral mechanism, and most traded fish are produced commercially.

Trichopsis schalleri is a croaking gourami from the lower Mekong basin and the Chao Phraya watershed in Thailand, Laos, Cambodia and Vietnam. Sometimes called the Mekong croaking gourami or three-stripe gourami, it is larger than the similar T. pumila, and its upper body stripe varies with mood and sometimes fades entirely. Peaceful unless breeding, it can be kept in a pair or a group.

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.

The banded gourami, Trichogaster fasciata, is a labyrinth fish from Pakistan, India, Nepal, Bangladesh and Myanmar, found in sluggish, weedy waters. The largest species in its genus, it is a popular food fish in its native countries. Peaceful, it suits most quiet community tanks, but should not be kept with the thick-lipped gourami because the two can hybridise.

Betta akarensis is a paternal mouthbrooding labyrinth fish from Borneo, collected in Brunei and the Malaysian state of Sarawak. It lends its name to the Betta akarensis group of closely related species and is considered one of the more widely distributed Bornean Betta. Most are collected from blackwater, though it also lives in clear flowing streams, roadside ditches and larger ponds.

The leopard bushfish, Ctenopoma acutirostre, is an anabantoid from the middle Congo River basin, from Malebo Pool upstream to Boyoma Falls. Often sold as 'spotted climbing perch', it mimics leaves and other debris to stalk its prey, much like the unrelated South American leaf fish. Exceptionally hardy and long-lived, it can survive for over 15 years and makes an ideal species for the newcomer to 'oddballs'.

Macropodus erythropterus is a paradisefish from coastal hill streams of central Vietnam, in Quang Binh and Quang Tri provinces. Occasionally traded, sometimes as 'red-backed paradisefish', it is often misidentified as M. spechti, which lacks red in the dorsal, anal and caudal fins. Whether the two represent the same taxon has been debated. A bubble nester, it is relatively peaceful unless breeding.

The black paradise fish, Macropodus spechti, is a labyrinth fish from central Vietnam, known with certainty from the Thu Bồn and Hương river systems. Its name is frequently misapplied to the similar-looking M. erythropterus, easily identified by reddish pigmentation in the dorsal, anal and caudal fins. Older literature sometimes refers to it as M. concolor. Relatively peaceful unless breeding, it is kept in pairs.

The ornate paradisefish, Malpulutta kretseri, is a labyrinth fish from the 'wet zone' of southwestern Sri Lanka. It has been recorded from the Gin, Kelani, Kalu, Nilwala and Bentota river basins. The only member of its genus, it is protected by law in Sri Lanka although it still appears in the aquarium trade from time to time. Three colour forms exist, differing in the amount of reddish, violet or bluish pigmentation in the fins.

Parasphaerichthys lineatus is a tiny gourami from the Irrawaddy delta, Myanmar, and at 15 to 19 mm SL the smallest member of the family Osphronemidae. It is sometimes traded as 'mini chocolate gourami' or 'Burmese chocolate gourami', or misidentified as P. ocellatus, from which it differs in its dark mid-lateral stripe and the lack of an ocellus on each flank.

The spiketail paradisefish, Pseudosphromenus cupanus, is a small labyrinth fish restricted to southern India and Sri Lanka. It lives in sluggish and still waters such as rice paddies, swamps and weedy ponds. It lacks the two dark lateral stripes of its only congener, P. dayi. A secretive bubble nester, it is peaceful but too small and timid for most community aquaria.

The brown spike-tailed paradise fish, Pseudosphromenus dayi, is a small labyrinth fish from coastal drainages of the Western Ghats in Kerala, India. It is known only from the Chalakkudy, Muvattupuzha and Periyar rivers, though it may be more widely distributed. Two dark, irregular lateral stripes on the head and body, and a more extended caudal fin in males, separate it from its only congener, P. cupanus. A secretive bubble nester, it is peaceful but small and timid.

The moonlight gourami, Trichopodus microlepis, is a labyrinth fish from Vietnam, Cambodia and Thailand. It inhabits lowland ponds, bogs and swamps where vegetation grows densely, and its modified ventral fins are considerably longer than in other gouramis. It is often used as a food fish in its native countries, and most fish on sale are mass-produced.

The snakeskin gourami, Trichopodus pectoralis, is a large labyrinth fish from the Mekong and Chao Phraya drainages of Indochina and Myanmar. Growing to 30 cm, it is farmed as a food fish, and feral populations are established in several countries as a result. A very peaceful species for the larger community tank, it can produce 'cracking' noises during breeding or territorial exchanges.

The three-spot gourami, Trichopodus trichopterus, is a labyrinth fish found mostly in the Mekong basin of Southeast Asia and southern China. The natural form is blue-grey with three spots, but gold, opaline, cosby, marbled and silver forms bred for the trade are seen far more often. One of the hardiest fish in the trade, it is recommended for community tanks with reservations, since some individuals become very spiteful as they mature.

The dwarf gourami, Trichogaster lalius, is a labyrinth fish from Pakistan, northern India and Bangladesh. All the fish in the trade are mass-produced, and several line-bred colour forms are sold, including 'Sunset' and 'Neon'. Stock quality has fallen badly, and mass-breeding may have spread dwarf gourami iridovirus (DGIV), which appears to be very infectious and can pass to other species sharing the water.

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 Ceylonese combtail, Belontia signata, is a labyrinth fish endemic to the central and southern river systems of Sri Lanka. Also referred to as the 'Ceylon fighting fish', it differs from B. hasselti in its reddish body and the absence of mosaic patterning in the unpaired fins. At least three putative phenotypes have been recorded, one described as the questionably valid subspecies B. s. jonklaasi. It is not recommended for the average community aquarium.

Betta albimarginata is a small mouthbrooding labyrinth fish that appears endemic to the Sebuku River drainage in East Kalimantan, Indonesian Borneo. It lives among marginal plant roots and leaf litter in forest streams only 5 to 10 cm deep. With B. channoides it forms the Betta albimarginata group, and the two look very similar: in B. albimarginata the unpaired fins have a broad white distal band and a broad dark submarginal band around a plain red inner portion.

Betta antoni is a mouthbrooding labyrinth fish that appears endemic to the lower Kapuas basin in West Kalimantan, Indonesian Borneo. Known as Betta sp. 'Sanggau' before its description, it belongs to the Betta akarensis group. It inhabits quiet margins and still pools in clear, flowing forest hill streams, and live fish show blue iridescence on the body scales and a distinct black lower lip.

Betta balunga is a mouthbrooding labyrinth fish from Borneo, found from Tawau in Sabah, Malaysia, south to the Sebuku and Mahakam basins in Indonesia. A member of the Betta akarensis group, it has a reddish-orange iris in life. In the Sebuku it lives in very shallow forest streams among roots and leaf litter, and in the Mahakam basin in sluggish blackwater streams among submerged marginal vegetation.

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.

Betta brownorum is a small bubble-nesting labyrinth fish endemic to Borneo, found in southern and western Sarawak and in West Kalimantan. A member of the B. coccina group, it is a stenotypic inhabitant of peat swamp forests and their blackwater streams. Both sexes carry a large iridescent green lateral blotch on a reddish-magenta body, though patterning within the group can be similar and confusingly variable.

Betta burdigala is a small bubble-nesting labyrinth fish endemic to the island of Bangka, off the east coast of Sumatra, Indonesia. A stenotypic inhabitant of peat swamps and blackwater streams, it belongs to the B. coccina group and is most similar to B. uberis. The species is exceptionally rare in the hobby, and many fish traded or pictured under its name are B. uberis or another congener.

The snakehead betta, Betta channoides, is a small mouthbrooding labyrinth fish from the Mahakam basin in East Kalimantan, Indonesian Borneo. It inhabits shallow forest streams with brownish, acidic water, among leaf litter and marginal plant roots. With the very similar B. albimarginata it forms the Betta albimarginata group, and displaying males are scarlet, with an almost entirely red dorsal fin edged by a thin white band.

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 cracens is a mouthbrooding labyrinth fish from the Jambi area of Sumatra, Indonesia, and it may also occur on nearby Bangka island. The most slender member of the B. pugnax complex, it is rare in the hobby, and most fish sold under the name are misidentified or mislabelled B. pugnax, B. raja or related species. Fish collected on Bangka have appeared in the hobby as Betta sp. 'Bangka'.

Betta dennisyongi is a small mouthbrooding labyrinth fish from the western coast of central Aceh province, northwestern Sumatra, Indonesia. It belongs to the B. rubra group and is typically exported mixed with the similar B. rubra, so the two may have been inadvertently hybridised before its description by Tan (2013). It has been collected among submerged leaf litter in lowland hill streams and acidic freshwater swamps.

Betta dimidiata is a small mouthbrooding labyrinth fish that appears endemic to the upper Kapuas drainage in West Kalimantan, Indonesian Borneo. It is often confused in the trade with B. krataios, formerly B. sp. 'Kapuas', but the caudal fin separates them: rounded in B. krataios, spade-shaped and more extended in adult B. dimidiata. It inhabits shaded forest swamp streams and pools, some only a few centimetres deep.

Betta edithae is a paternal mouthbrooding labyrinth fish from Indonesia, recorded across Kalimantan, southern Sumatra, Bangka, Belitung and Bintan. The only member of the B. edithae group, it is separated from all other Betta spp. by its opaque or translucent branchiostegal membrane and posterior opercle. Fish from Bintan differ from Bornean specimens in several characters, and it remains unclear whether all populations are conspecific.

Betta enisae is a paternal mouthbrooding labyrinth fish known only from parts of the River Kapuas basin in West Kalimantan, Indonesian Borneo. A member of the B. pugnax complex, whose species are notoriously difficult to tell apart, it has transverse bars in the caudal fin. Populations differ in colour and pattern and are often labelled with collection details such as Putussibau or Sentarum. It inhabits cool, shaded forest streams and swamp pools stained with humic acids.

Betta falx is a small paternal mouthbrooding labyrinth fish endemic to Sumatra, Indonesia, where most collections come from Jambi province. A member of the B. picta group, it has greenish blue iridescent opercular scales and a reddish distal band on the anal and caudal fins. It inhabits shaded forest swamp streams and pools, some only a few centimetres deep, with negligible mineral content and a low pH.

Betta foerschi is a paternal mouthbrooding labyrinth fish from a handful of localities in Central and West Kalimantan, Indonesian Borneo. It lends its name to the B. foerschi group, whose members have iridescent blue or green unpaired fins and two reddish-yellow bars on the opercle. Fish traded as B. foerschi are often the closely-related B. mandor, and the two can be difficult to tell apart.

Betta gladiator is a large paternal mouthbrooding labyrinth fish presumed endemic to the isolated Maliau basin in Sabah, Malaysian Borneo. A member of the B. unimaculata complex, it grows to 90 mm SL. The type series came from heath forest with acidic water of pH 4.2-4.8, where adults were spaced around a metre apart and usually accompanied by a few juveniles. It has a reputation for aggression.

Betta hendra is a small bubble-nesting labyrinth fish known only from the Sabangau peat swamp forest near Palangkaraya, Central Kalimantan, Borneo. A member of the B. coccina group, it has bright iridescent green flanks and fins where most of its relatives are red. It has been traded as B. sp. 'Sengalang/Palangkayara' and B. sp. 'Sebangua'. The type locality is still, shaded blackwater with a pH around 4.0.

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.

Betta ibanorum is a paternal mouthbrooding labyrinth fish from southern and western Sarawak, Borneo, where it exists in several colour forms. Most known localities are blackwater peat swamps, but it has also been collected from clear streams, roadside ditches and a pool at the top of a waterfall. A member of the B. akarensis group, it is uncommon in the hobby and apparently more often fished for food.

Betta ideii is a large paternal mouthbrooding labyrinth fish from southern South Kalimantan and Pulau Laut, Indonesian Borneo. Traded as B. sp. 'Laut' before its description, it belongs to the B. unimaculata complex and grows to 110 mm SL. It looks very similar to its closest relative B. patoti but lacks dark vertical bars on the flanks, and adult males are much darker.

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 krataios is a paternal mouthbrooding labyrinth fish that appears endemic to the lower River Kapuas basin in West Kalimantan, Indonesian Borneo. Traded as B. sp. 'Kapuas' before its description, it is sometimes confused with B. dimidiata, the other member of the B. dimidiata group. The two are easily told apart since the caudal fin is rounded in B. krataios and spade-shaped and more extended in B. dimidiata.

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 lehi is a paternal mouthbrooding labyrinth fish endemic to Borneo, in southwestern Sarawak and the lower River Kapuas basin in West Kalimantan. A member of the B. pugnax complex, it has green iridescent scales on the opercle and body and a light blue iridescent band on the anal fin. It inhabits forest peat swamps, acidic clearwater swamps and associated streams, where the pH can be between 3.0 and 5.5.

Betta livida is a small bubble-nesting labyrinth fish endemic to peat swamps in northern Selangor state, Peninsular Malaysia. A red member of the B. coccina group, it has a small iridescent green lateral blotch that fades with age. Much of its range has been turned over to oil palm or rubber plantations, and it is listed as endangered by the IUCN, so captive reproduction should be the priority for anyone keeping it.

The Brunei beauty, Betta macrostoma, is a large paternal mouthbrooding labyrinth fish endemic to Brunei and the northern tip of Sarawak, Borneo. It grows to 100 mm SL, and males are red with a red patch on the opercle and an ocellus in the dorsal fin. It lives in still, shady pools at the top of rainforest waterfalls. Listed as Vulnerable by the IUCN, it has been banned from export by the Sultan of Brunei.

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 mandor is a paternal mouthbrooding labyrinth fish from near Mandor and Anjungan in the lower Kapuas basin, West Kalimantan, Borneo. Known as B. sp. 'Mandor' or B. sp. 'ninja' before its description, it belongs to the B. foerschi group. Males are black and females brown, with twin red bars on the opercle. It is sometimes traded as B. foerschi, and the two can be difficult to tell apart.

Betta midas is a stout-bodied labyrinth fish from the lower Kapuas basin in West Kalimantan, Indonesian Borneo, and may also occur in western Sarawak. It has been traded as B. anabatoides in the past, and most images of it are labelled as such. It has gold iridescent scales on the opercle, belly and body. The paratype series came from a blackwater river in peat swamp forest with a pH of 4.1.

Betta miniopinna is a small bubble-nesting labyrinth fish endemic to Bintan Island, Indonesia, where it is known from a few northern localities. A dark member of the mostly red B. coccina group, it is most similar to B. persephone. Development for tourism and rubber plantations has left it restricted to a few pockets of primary peat swamp forest, and it has been listed as Critically Endangered on the IUCN Red List since 1996.

Betta ocellata is a large paternal mouthbrooding labyrinth fish from Sabah, northeastern Borneo, and the Sebuku River basin in East Kalimantan. A member of the B. unimaculata complex, it grows to 90 mm SL and has a pointed, slightly conical head. It has been collected from clear flowing streams, elevated headwater pools, turbid forest streams, ox-bow lakes and ponds in oil palm plantations.

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 pardalotos is a large paternal mouthbrooding labyrinth fish from the Musi drainage near Palembang, South Sumatra, Indonesia. A member of the B. waseri group, it is best told from its relatives by the throat, which has two white, roundish patches on a black background. It is possibly endemic to the lower Musi basin, and the type series came from small freshwater channels draining into the river.

Betta patoti is a large paternal mouthbrooding labyrinth fish from East Kalimantan, Borneo, described from the Mangar River near Balikpapan. A member of the B. unimaculata complex, it grows to 100 mm SL and has 10-14 dark vertical bars on the lower body. Colour varies with locality, from blackish-barred fish around Balikpapan to more reddish ones further north.

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.

The spotted betta, Betta picta, is a small paternal mouthbrooding labyrinth fish known only from Java, Indonesia. It lends its name to the B. picta complex and has iridescent yellow-gold opercle scales. It is usually found in quiet margins and still pools of clear, flowing hill streams, but has also been collected from roadside ditches and water tanks.

Betta pinguis is a paternal mouthbrooding labyrinth fish known only from the middle and upper Kapuas watershed in West Kalimantan, Indonesian Borneo. A member of the B. akarensis group, it has a relatively stocky body and dense dark markings on the opercle below the postorbital stripe. The type specimens came from a small, slightly tannin-stained stream in degraded forest, where B. dimidiata and B. enisae also occur.

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 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.

Betta raja is a mouthbrooding labyrinth fish endemic to Sumatra, Indonesia, found in the Batang Hari and Indragiri river basins. Before its description it was widely misidentified as Betta fusca. It lives in lowland forest swamps with both clear and black water, and mature males of this B. pugnax complex member have very long pelvic fins and black marginal bands on the anal and lower caudal fins. Populations from different localities should be labelled as such to preserve pure bloodlines.

Betta rubra is a small labyrinth fish from northwestern Sumatra, Indonesia, known from the Singkil area of Aceh and around Sibolga in North Sumatra. Conflict in the region meant it was known only from the type specimens for around 100 years, and it began to appear in the hobby in early 2007. It is typically exported mixed with the similar-looking B. dennisyongi and may have been hybridised with it. The two are told apart mainly by the opercle pattern and the width of the triangular black mark below the eye.

Betta rutilans is a small, deep red labyrinth fish from peat swamps near Anjungan in West Kalimantan, Borneo, Indonesia. Known in the hobby as B. sp. 'Anjungan' before its description, it belongs to the B. coccina group, whose members can be hard to identify because their patterning is similar and confusingly variable. B. rutilans has a uniformly deep red body with no midlateral blotch. A bubble-nester, it lives in blackwater streams where the pH can be as low as 3.0 or 4.0.

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 simorum is a slender bubble-nesting labyrinth fish from Sumatra and the Kapuas River system in West Kalimantan, Borneo, Indonesia. Growing to around 90 mm SL, it inhabits heavily-vegetated forest peat swamps and blackwater streams. It shares the B. bellica group with B. bellica, from which it differs in its slanted head with a concave profile behind the eye. Populations are often labelled by locality, such as Rantau Panjang or Sungai Bengkwan, to preserve pure bloodlines.

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.

Betta sp. 'Antuta/Bulungan' is an undescribed mouthbrooding labyrinth fish from Bulungan Regency in East Kalimantan, northern Indonesian Borneo. It appears to be a member of the B. unimaculata complex, and its habitat is thought to be flowing highland streams. Adult size is unconfirmed but likely to be 90 to 100 mm. Relatively peaceful, it can be kept in a group in a tank of sufficient size with plenty of hiding places.

Betta spilotogena is a mouthbrooding labyrinth fish from Bintan and Singkep islands in the Riau Islands province of Indonesia. It inhabits shaded freshwater swamps and streams with clear or lightly tannin-stained water less than a metre deep, alongside B. edithae, B. miniopinna and B. fusca. A member of the B. waseri group, it has a single dark, pear-shaped blotch on the throat that is not joined to the black lower lip.

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.

Betta stigmosa is a mouthbrooding labyrinth fish from forest hill streams in Terengganu state, Peninsular Malaysia. The type specimens came from a stream draining into the Sekayu waterfalls near Kuala Berang, and it has since been recorded around 150 km to the south. Its streams carry clear, flowing water over rocks, gravel and leaf litter. In this member of the B. pugnax complex both sexes have transverse bars in the dorsal, anal and caudal fins.

Betta taeniata is a mouthbrooding labyrinth fish endemic to Borneo, known from southern Sarawak in Malaysia and northern West Kalimantan in Indonesia. It is usually associated with clear, flowing hill streams, where it lives in quiet marginal zones and still pools among leaf litter and gravel. A member of the B. picta group, it has a yellowish body and fins and a blackish head. Populations such as Sri Aman, Serian and Kapuas are often labelled by locality to preserve pure bloodlines.

Betta tussyae is a small bubble-nesting labyrinth fish endemic to coastal Pahang and Terengganu states in eastern Peninsular Malaysia. This poorly-known member of the B. coccina group is an obligate inhabitant of peat swamps and blackwater streams, where the pH can be as low as 3.0 or 4.0. Its reddish orange body with two darker lateral stripes and faint gold vertical bars on the opercle separate it from similar group members. Populations such as Chukai and Rompin are often labelled by locality.

Betta uberis is a small bubble-nesting labyrinth fish from peat swamp forests in Central and West Kalimantan, Borneo, Indonesia. Most records come from between the lower Arut and Kumai rivers near Pangkalan Bun. Known to aquarists as Betta sp. 'Sukadana' or B. sp. 'Pangkalanbun' before its description, it belongs to the B. coccina group and is named for its high count of 14 to 17 dorsal-fin rays, which also separates it from its nearest neighbour in the group, B. hendra.

Betta unimaculata is a large mouthbrooding labyrinth fish from the upper Kayan and Mahakam river drainages in East Kalimantan, Borneo, Indonesia. Growing to around 115 mm SL, it has been collected from clear, flowing streams, elevated headwater pools and more turbid forest streams. Populations differ in colour and pattern and will hybridise, so they are labelled by locality and should never be kept together. Fish from 'Tawau' once thought to be this species have been described as B. ocellata.

The ocellated bushfish, Ctenopoma muriei, is one of the smallest members of its genus, recorded from Egypt and Sudan south to Tanzania and Zambia. It lives in sluggish or still waters such as pools, lagoons and swamps, many of them low in dissolved oxygen. Rarely seen in the trade, it will eat only the tiniest fish and suits an African community with Alestiid tetras, dwarf cichlids and small Mochokid catfish.

The frail gourami, Ctenops nobilis, is an anabantoid from the Ganges and Brahmaputra systems in northeastern India, Bangladesh and Nepal. The only recognised member of its genus and a paternal mouthbrooder, it is usually regarded as very difficult to keep but is quite adaptable once acclimatised. It appears to react poorly to export and shipping, so imports are often in poor condition and prone to Oödinium. Adults can be openly hostile towards conspecifics.

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.

Macropodus hongkongensis is a paradisefish from Hong Kong and the neighbouring Chinese provinces of Guangdong and Fujian. In Hong Kong it is now known only from Tai Po and Sai Kung districts. It lives in hill streams and lowland, sometimes agricultural, habitats, apparently preferring shallow, densely vegetated water with slow flow. Males are territorially aggressive, especially when breeding, and the species is a bubble nester that is occasionally available in the trade.

The roundtail paradise fish, Macropodus ocellatus, is a labyrinth fish with an enormous range in China, Korea and Japan, north to the Amur River. It lives in ditches, rice paddies, marshes and river backwaters, where winter can freeze the surface and drop the water to 3 °C. It is sometimes referred to as M. chinensis in older literature, a name now considered a synonym of M. opercularis. Males are territorial when breeding and build bubble nests.

The paradise fish, Macropodus opercularis, is a labyrinth fish from China south of the Yangtze, including Taiwan and Hainan, plus Vietnam and Laos. Imported to France in 1869, it was among the very first ornamental fish brought to Europe. Wild examples are uncommon in the hobby since it is farmed extensively, and xanthic, albino, red, blue and stripeless strains exist. Males are territorially aggressive, especially when breeding, and should not be housed together unless the aquarium is very large.

The banded ctenopoma, Microctenopoma fasciolatum, is an anabantoid from the Congo basin and a handful of rivers in Cameroon. In nature it is found in clear water with plenty of surface and overhanging vegetation. Less shy than M. ansorgei, it is still slow-moving and easily out-competed by boisterous species. Males are territorial. A bubblenester, it has been bred in captivity.

The elephant ear gourami, Osphronemus exodon, is a large gourami from Thailand, Laos and Cambodia. Its greatly enlarged teeth, with an extra set in concentric bands on the outer lips, stay visible when the mouth is closed and are used to pick fruit from overhanging branches. Reaching 60 cm, it inhabits still or slow-moving areas of large rivers and enters flooded forest in the rainy season.

The giant gourami, Osphronemus goramy, is a large gourami from Borneo, Java, Sumatra, Thailand, Indo-china and the Malay Peninsula. Reaching 70 cm and living for over 20 years, it is often sold as a juvenile with no information on its adult size. It is cultured for food on a large scale, a golden variety exists in aquaria, and dyed fish are produced by injecting colour under the skin.

The giant red tail gourami, Osphronemus laticlavius, is a large gourami from Indonesia and Malaysia, described to science in the early 1990s. Adults develop bright red fin edges with filamentous extensions and a body colour between blue-green and almost black. It reaches 50 cm and probably inhabits slow-moving rivers and other sluggish or stagnant water.

The eyespot gourami, Parasphaerichthys ocellatus, is a small anabantoid from the upper Ayeyarwady basin in northern Myanmar, including Lake Indawgyi. It shares the trade names 'mini chocolate gourami' and 'Burmese chocolate gourami' with P. lineatus, but grows larger, to 32 mm SL, and has an ocellus-type marking in the middle of each flank with no dark mid-lateral stripe. In nature it is subject to seasonal temperature fluctuations and is comfortable between 15 and 25 °C.

Parosphromenus alfredi is a liquorice gourami endemic to a small part of eastern Johor, Peninsular Malaysia, around Kota Tinggi, Mawai and Desaru. A stenotypic inhabitant of peat swamp forests and blackwater streams, it has lost a great deal of its habitat and is considered in grave danger of extinction. It is most similar to P. phoenicurus, which has a rhombic caudal fin, and P. tweediei, which lacks blue markings in the unpaired fins.

Parosphromenus allani is a liquorice gourami from Sarawak in Borneo, East Malaysia, to which it appears endemic. Its type description was a hobbyist-magazine announcement with limited diagnostic information, and fish from around Lundu with a different fin pattern, known to aquarists as P. sp. 'Stunggang' or P. sp. 'Lundu', may or may not be the same species. Much of its habitat has been lost and it is considered in grave danger of extinction.

Parosphromenus anjunganensis is a liquorice gourami known only from a handful of localities near Anjungan in Kalimantan Barat, Indonesian Borneo. Males have uniformly reddish-brown dorsal, anal and caudal fins with a thin bluish to whitish margin. A stenotypic inhabitant of peat swamp forests and blackwater streams, it may be highly threatened, since some habitats in its range have been cleared and drained for agriculture.

Parosphromenus bintan is a liquorice gourami from Indonesia, confirmed only from Bintan Island in the Riau Archipelago and from Bangka. Similar-looking fish from Sumatra and Borneo may or may not be conspecific, and the name is sometimes misapplied to commercial shipments of other species. Males have a rounded caudal fin with concentric whitish, black, bluish and broad black or reddish-black bands.

Deissner's liquorice gourami, Parosphromenus deissneri, is endemic to the island of Bangka in Indonesia, mostly in its northern and eastern portions. For almost a century after its description in 1859 it was the only recognised member of the genus, so its name has been widely misapplied in aquarium and ichthyological literature, though it's probably always been very rare in the hobby. Males have pale subdistal bands of oval spots in the unpaired fins.

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 linkei is a liquorice gourami from Central Kalimantan province in Indonesian Borneo, described from creeks near Sukamara. Said to be slightly easier to maintain than most congeners, it has been traded as 'moonspot licorice gourami'. Males have one to three black blotches in the midlateral stripe and a lanceolate caudal fin, and populations that differ in colour should be kept apart. It appears 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 opallios is a liquorice gourami endemic to Central Kalimantan province in Indonesian Borneo, in the Arut and Benipah river systems. It appeared in the trade on a handful of occasions as P. sp. 'Sukamara' before its description, and occurs alongside P. linkei at Sukamara. A stenotypic inhabitant of peat swamp forests and blackwater streams, it appears in danger of extinction.

Parosphromenus ornaticauda is a liquorice gourami from West Kalimantan, Indonesian Borneo, in the Kapuas drainage near Anjungan and the Pawan system. Sometimes sold as 'ornate licorice gourami', it has occasionally appeared in the trade in substantial quantities but is not easy to maintain and is often susceptible to disease post-import. Males are identified by their caudal-fin pattern and the large amount of black in the dorsal and anal fins.

Parosphromenus quindecim is a liquorice gourami known only from the Pawan and Liong river basins in West Kalimantan, Indonesian Borneo. Before description it was traded as P. sp. 'Manis Mata', though that name apparently refers to a place some 100 km from the type locality where the fish do not occur. Said to be slightly easier to maintain than most congeners, it occurs alongside P. ornaticauda at some localities.

Parosphromenus sp. 'Sentang' is a liquorice gourami said to come from Jambi province, central Sumatra, Indonesia, presumably the Sentang river. It is sometimes referred to by the invented name P. 'sintangensis'. It closely resembles P. bintan and P. sp. 'blue line', though the inner bluish bands in its dorsal, anal and caudal fins are perhaps a little narrower. Its habitat is unconfirmed.

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.

The Cape kurper, Sandelia capensis, is an anabantoid endemic to the Cape Province, South Africa, found in the middle to lower reaches of many rivers. Its habitats are being destroyed and its numbers declining through introduced predators, damming, pollution and climatic changes. Genetic studies have revealed at least two, possibly several, deep lineages, and these would appear to indicate multiple species.

The giant chocolate gourami, Sphaerichthys acrostoma, is a small gourami known only from the Mentaya River drainage in Indonesian Borneo. It is far from common in the hobby and is traded under several other names, including 'sharp-nosed gourami'. Its colour pattern sets it apart from the other members of the genus. A paternal mouthbrooder, it chiefly inhabits peat swamps and associated black water streams.

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.

The crossband chocolate gourami, Sphaerichthys selatanensis, is a small labyrinth fish from southern Borneo, Indonesia. It probably inhabits peat swamps and associated black water streams, and is only occasionally seen in the hobby, sometimes sold as 'cherry chocolate gourami'. Originally described as a subspecies of S. osphromenoides, it differs in fin-ray counts and an additional light vertical bar on each flank.

Vaillant's chocolate gourami, Sphaerichthys vaillanti, is a labyrinth fish that appears to be endemic to the Kapuas drainage in Indonesian Borneo. It is also traded as the 'samurai gourami', a misleading name since the fish is neither especially combative nor from Japan. Unlike S. osphromenoides and S. selatanensis it is a paternal mouthbrooder, and females carry alternating red and green vertical bars.

The climbing perch, Anabas testudineus, is a labyrinth fish found from Pakistan and Sri Lanka east to southern China, Indonesia and Singapore. It lives in almost every kind of lowland water from rice paddies to main river channels, and can cross several hundred metres of land provided it stays moist. Its taxonomy is confused, and additional taxa probably exist. Its size and predatory nature make it unsuitable for the general community.

The green throat mouthbrooder, Betta chloropharynx, is a labyrinth fish described from Bangka, an island off the east coast of Sumatra, Indonesia. A member of the Betta waseri group, it is told apart from all others in the group by its lighter throat markings, which form a shape like a horizontal figure of eight. It generally inhabits peat swamps and blackwater streams, and a Sumatran population once thought conspecific was described as B. pardalotos in 2009.

Betta pallifina is a large paternal mouthbrooding labyrinth fish from a remote part of the upper Barito basin in Central Kalimantan, Borneo. A member of the B. unimaculata complex, it grows to 90 mm SL, and females have an orange band in the anal fin. It inhabits forested headwater streams with clear, flowing water, dense marginal plants and a pH of 6.6-7.4.

The tailspot ctenopoma, Ctenopoma kingsleyae, is an anabantoid with an enormous range, recorded from Mauritania and Senegal to Gabon and the DR Congo. One of the more aggressive members of the genus, it can be particularly nasty towards conspecifics and will eat small fish. It is named after the explorer Mary Kingsley, and there are reports of specimens surviving in aquaria for over 30 years.

The mottled bushfish, Ctenopoma weeksii, is an anabantoid from the River Congo drainage in the Republic of Congo and Democratic Republic of Congo. It lives in sluggish, often hypoxic waters, usually among the thickest marginal vegetation. A predator of small fish but otherwise retiring, it can be kept in a group if all the fish are added at the same time.

The giant pikehead, Luciocephalus pulcher, is a predatory anabantoid from blackwater peat swamps in Thailand, Malaysia, Indonesia and Brunei. Highly piscivorous and notoriously difficult to wean off live foods, it travels poorly and is often sold in a weakened, emaciated state. Once settled it is quite hardy. The male is a mouthbrooder, holding the eggs for around 30 days, and it is best kept in a species tank in acidic water.

The ornate ctenopoma, Microctenopoma ansorgii, is an anabantoid from the Congo basin in the Republic of Congo and Democratic Republic of Congo. The most colourful of the African anabantoids, it is relatively rare in the hobby because its habitat of densely vegetated small streams is hard to collect from. It can be difficult to acclimatise but is very hardy once settled, and it is a slow-moving fish that is easily out-competed at feeding time.

Betta renata is a mouthbrooding labyrinth fish from forest peat swamps in Jambi, South Sumatra and Riau provinces on Sumatra, Indonesia. A member of the B. waseri group, it is most easily identified by a clearly-defined dark, kidney-shaped blotch on the throat that is always separate from the dark lower jaw. Its blackwater habitats can have a pH as low as 3.0 or 4.0, and at certain times of year the fish may be forced to survive in moist leaf litter for several weeks.

The Eastern Cape rocky, Sandelia bainsii, is an anabantoid endemic to a handful of river systems in the southeastern Cape, South Africa. Listed as endangered by the IUCN since 1994, it occurs in short sections of only half a dozen rivers. A conservation project begun in 1991 at the Blaauwkrantz Nature Reserve has released captive-bred fish at several sites. Sandelia spp. have a less well-developed labyrinth organ than their relatives.