Schistura maepaiensis KOTTELAT, 1990

Etymology

Schistura: from the Greek schizein, meaning ‘to divide’, and oura, meaning ‘tail’, in reference to the caudal-fin shape of many species.

maepaiensis: named for Mae Nam Mae Pai, where the species was first collected.

Classification

Order: Cypriniformes Family: Nemacheilidae

Distribution

Type locality is ‘Nam Mae Cha at Ban Pha Bong, 19°12’N, 97°59’E, 12 kilometers south of Mae Hong son, Mae Hong Son Province, Salween basin, Thailand’, and S. maepaiensis is known only from tributaries of the Salween River basin in Mae Hong Son and Tak provinces, northwestern Thailand.

It may also occur in the Salween system in Myanmar.

Habitat

The type locality originally consisted of a shallow (0.5 – 1.5 m deep) stream with a substrate of rocks and boulders and flow varying from ‘moderate to swift’.

When the holotype was collected there in 1980 sympatric species included Acanthocobitis zonalternans, Puntius orphoides, Pethia ticto, Raiamas guttatus, Barilius barnoides, Mystacoleucus argenteus and Mastacembelus armatus plus unidentified members of Crossocheilus and Glyptothorax.

Unfortunately just five years later the habitat had been seriously degraded by human activity, fish populations were much lower, those in evidence showed signs of illness and S. maepaiensis was not recorded.

Healthy populations do exist however, a fact exemplified by the species‘ occasional appearance in the aquarium trade, and presumably consist of similar well-oxygenated, forest-shaded streams and minor tributaries.

In the Suriya River which joins the Salween in Myanmar (where it’s known as the Hanthayaw River) other species include Acanthocobitis pictilis, Syncrossus berdmorei, Botia kubotai, Microdevario kubotai, Tetraodon cutcutia, Crossochilus burmanicus, Homalopteroides modestus and Hampala salweenensis.

Maximum Standard Length

40 – 45 mm.

Aquarium SizeTop ↑

Even a small group will need an aquarium with base dimensions of 80 ∗ 30 cm or similar.

Maintenance

Not difficult to maintain under the correct conditions. We strongly recommend keeping it in a tank designed to resemble a flowing stream or river with a substrate of variably-sized rocks, sand, fine gravel, and some water-worn boulders.

This can be further furnished with driftwood branches arranged to form a network of nooks, crannies, and shaded spots, thus providing broken lines of sight.

While the majority of aquatic plants will fail to thrive in such surroundings hardy types such as Microsorum, Bolbitis, or Anubias spp. can be grown attached to the décor.

Once acclimatised individuals tend to select a particular cave or sheltered space which they defend against conspecifics and similar-looking species so it’s important to provide a well-structured environment.

In this kind of set-up it will thrive and can be kept alongside other species that enjoy similar conditions (see ‘Behaviour and Compatibility’).

Though torrent-like conditions are unnecessary it does best if there is a high proportion of dissolved oxygen and some water movement in the tank so power filter(s), additional powerhead(s), or airstone(s) should be employed as necessary.

Like many fishes that naturally inhabit running water it’s intolerant to accumulation of organic pollutants and requires spotless water in order to thrive. Weekly water changes of 30-50% tank volume should therefore be considered routine.

Water Conditions

Temperature: 20 – 26 °C

pH: 6.0 – 7.5

Hardness: 36 – 215 ppm

Diet

Schistura species are omnivorous although the bulk of their diet consists of small insects, worms, crustaceans, and other zooplankton with only relatively small amounts of plant matter and other organic detritus consumed.

In the aquarium they will accept dried foods of a suitable size but should not be fed these exclusively.

Daily meals of small live and frozen fare such as Daphnia, Artemia, bloodworm, etc., will result in the best colouration and condition. In a set-up with moving water they will often shoot up to snatch morsels passing in the flow.

Behaviour and CompatibilityTop ↑

Not especially aggressive compared with some members of the genus but remains largely unsuitable for the ‘general’ community aquarium due to its somewhat specialised requirements.

This is not to say it must be kept alone, rather that tankmates must be selected with care and proper research.

Slow-moving or long-finned species should certainly be omitted because they’re likely to struggle with the necessary level of water movement and may end up with nipped fins.

Placid bottom-dwellers such as Corydoras or Pangio spp. also tend to be easy targets for territorial Schistura and are best avoided.

Fishes which inhabit similar biotopes in nature, especially those which swim in open water such as Danio, Devario, Mystacoleucus, smaller Barilius, Pethia, Puntius, and Rasbora spp. constitute the best options, and one or two schools can make a visible difference to the confidence of this naturally reclusive loach.

Other possibilities include current-loving loaches from genera such as Pseudogastromyzon, Beaufortia, or Sewellia plus benthic cyprinids such as Crossocheilus and Garra spp.

Similarly-shaped relatives like Nemacheilus, Acanthocobitis, and other Schistura spp. aren’t recommended under most circumstances although a combination may work in larger aquaria.

While it can’t be described as gregarious a group can be maintained together provided the set-up contains plenty of rocky structures and broken lines of sight.

Occasional skirmishes may occur, however, and in small or sparsely-decorated tanks conspecific aggression may escalate to an unacceptable level.

Sexual Dimorphism

Males have a suborbital flap and noticeably longer pectoral fins with small tubercules on some rays.

Females should be slightly thicker-bodied, especially when full of eggs.

Reproduction

Unrecorded.

NotesTop ↑

This species is poorly-known in the aquarium hobby.

It can be told apart from other members of the genus by its unique patterning consisting of 10-13 irregular body bars with thin dark borders.

Other distinguishing features include: 9+8 branched caudal-fin rays; 9-10½ branched dorsal-fin rays; possession of a suborbital flap in males; complete lateral line; axillary pelvic lobe present; eye diameter larger than or equal to interorbital width; black bar at caudal-fin origin split to form two spot-like markings.

Schistura is the most species-rich genus among nemacheilid loaches with some 190 members and it continues to grow with over 100 having been described since 1990. It may represent a polyphyletic lineage and is often arranged into a number of loosely-defined species ‘groups’, some of which are quite dissimilar to one another.

Among these are an assemblage in which some or all of the body bars are vertically split and another which exhibit reductions in body size (adult size <50 mm SL), the number of pelvic and pectoral-fin rays and often the number of caudal-fin rays and lateral line length, for example.

Some species, such as S. geisleri, also appear to be unrelated to any of the others.

Most inhabit flowing streams or areas close to waterfalls where there naturally exist high concentrations of dissolved oxygen, and a handful are troglobytic, i.e., cave-dwelling, in existence. The latter have reduced pigmentation and are completely blind in many cases.

Schistura spp. are distinguished from other nemacheilids by a combination of morphological characters which include: a moderately arched mouth which is 2-3.5 times wider than it is long; a median ‘interruption’ in the lower lip which does not form two lateral triangular pads and can vary from smooth to furrowed in texture; diverse colour pattern but usually dark with relatively regular bars; usually a black bar at the caudal-fin base which can be broken into two spots or smaller bars; one or two black markings along the base of the dorsal-fin; lack of acuminate scales on the caudal peduncle; caudal-fin shape variable from truncate to forked but usually emarginate; presence or absence of a median notch in the lower jaw; clear sexual dimorphism in some species.

The family Nemacheilidae is widely-distributed across most of Eurasia with the Indian subcontinent, Southeast Asia and China representing particular centres of species diversity.

References

1. Akan, F. E., T. T. Nalbant and S. C. Özeren, 2007 - Journal of Fisheries International 2(1): 69-85
   Seven New Species of Barbatula, Three New Species of Schistura and a New Species of Seminemacheilus (Ostariophysi: Balitoridae: Nemacheilinae) from Turkey.
2. Kottelat, M., 1990 - Verlag Dr. Friedrich Pfeil, München: 1-262
   Indochinese nemacheilines. A revision of nemacheiline loaches (Pisces: Cypriniformes) of Thailand, Burma, Laos, Cambodia and southern Viet Nam.
3. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
4. Kottelat, M., 2013 - Raffles Bulletin of Zoology Supplement No. 27: 1-663
   The fishes of the inland waters of southeast Asia: a catalogue and core bibiography of the fishes known to occur in freshwaters, mangroves and estuaries.
5. Tang, Q., H. Liu, R. Mayden and B. Xiong, 2006 - Molecular Phylogenetics and Evolution 39(2): 347-357
   Comparison of evolutionary rates in the mitochondrial DNA cytochrome b gene and control region and their implications for phylogeny of the Cobitoidea (Teleostei: Cypriniformes).
6. Šlechtová, V., J. Bohlen and H. H. Tan, 2007 - Molecular Phylogenetics and Evolution 44(3): 1358-1365
   Families of Cobitoidea (Teleostei; Cypriniformes) as revealed from nuclear genetic data and the position of the mysterious genera Barbucca, Psilorhynchus, Serpenticobitis and Vaillantella.