Schistura aurantiaca PLONGSESTHEE, PAGE & BEAMISH, 2011

Etymology

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

aurantiaca: from the Latin adjective aurantiaca, meaning ‘orange-coloured’, in reference to the orange vertical bars on the flanks of this species.

Classification

Order: Cypriniformes Family: Nemacheilidae

Distribution

Type locality is ‘Kwai Noi River system, Khayeng River at Route 3272 bridge, 14°39’35″N, 98°32’01″E, Mae Khlong basin, Thong Pha Phum, Kanchanaburi Province, Thailand’, and this species is currently known only from Kanchanaburi.

Habitat

Like related species it inhabits riffles and flowing stretches of clear, well-oxygenated  headwater streams and minor tributaries.

These are typically shaded by forest cover with substrates composed of coarse sand, gravel, rocks, and boulders and no aquatic plants, though riparian vegetation is normally well-developed.

During collections of the type series stream width was found to vary seasonally but was never wider than 9.1 metres. Water depth was 10-40 cm, flow rate 20-70 cm/s−1, and substrates comprised small to medium-sized rocks.

Water temperature was seasonally variable but always within the range 20-26°C/68-78.8°F, pH was 6.5-7.9, oxygen 7.4-8.5 mg/l−1, ammonia, nitrate and total iron were 0.01, < 0.03 and < 0.5 mg/l−1, respectively, and alkalinity was around 65 mg/l−1 except during floods when it decreased to 20 mg/l−1.

Sympatric fish species across three habitats included Danio albolineatus, Danio sp., Devario regina, Garra sp., Mystacoleucus marginatus, Neolissochilus stracheyi, Pethia stoliczkana, Puntius orphoides, Osteochilus vittatus, Rasbora paviana, Lepidocephalichthys berdmorei, Acanthocobitis zonalternans, A. botia, Nemacheilus pallidus, Schistura desmotes, S. mahnerti, Homalopteroides smithi, Homaloptera sexmaculata, Batasio tigrinus, Pseudomystus siamensis, Pterocryptis buccata, Amblyceps variegatum, Xenentodon cancila, Badis khwae, Mastacembelus armatus and Channa gachua.

The habitat in our images runs through a forested area with the tree canopy some 50 m above. It is 1.5 m wide, never more than 20 cm deep, and contains very clear, cool water, while the substrate consists of gravel, small rocks and larger boulders.

A species of Microsorum grows emerse around the margins and other fishes included a very brightly-coloured form of the congener S. balteata.

Maximum Standard Length

The largest-known specimen measured 39.7 mm.

Aquarium SizeTop ↑

Minimum base dimensions of 75 ∗ 30 cm or equivalent should prove sufficient.

Maintenance

Should not prove 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.

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 meaning 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, meaning weekly water changes of 30-50% tank volume should be considered routine.

Water Conditions

Temperature: 20 – 26 °C

pH: 6.5 – 8.0

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 ↑

Likely to prove similar to other members of the genus.

Sexual Dimorphism

None apparent according to the description paper.

Reproduction

Unreported.

NotesTop ↑

May not yet have appeared in the aquarium hobby although possibly exported alongside similar-looking species such as S. cf. balteata.

It can be told apart from congeners solely by its unique colour pattern which comprises 3-9 vertical orange bars on each flank. The first bar is immediately behind the head and the second in front of or otherwise close to the dorsal-fin origin, while most of the nape and anterior portion of the body are a uniform brown colour.

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. Plongsesthee, R., L. M. Page, and W. Beamish, 2011 - Ichthyological Exploration of Freshwaters 22(2): 169-178
   Schistura aurantiaca, a new species from the Mae Khlong basin, Thailand (Teleostei: Nemacheilidae).
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.