Schistura pridii VIDTHAYANON, 2003

Mini Dragon Loach

Etymology

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

pridii: named for the late Professor Pridi Bhanomyong, who founded Thammasart University, Bangkok, Thailand.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Endemic to a handful of tributary streams within the upper Chao Phraya river system in northern Thailand. Six populations are known to date, with the majority lying inside the Doi Chiang Dao Wildlife Sanctuary.

Type locality is ‘Stream Nam Muen, a tributary of river Mae Taeng, upper Chao Phraya basin, Chiangmai Province, Thailand’.

Habitat

An exclusive inhabitant of swiftly-flowing, shallow, pristine forest hill streams at around 950-1250 m AMSL.

These are typically less than 1 m deep with substrates of gravel, rocks, and boulders. Flow rate varies with the seasons but is torrential at certain times of year.

Sympatric species include Devario maetaengensis, Barilius pulchellus, Neolissochilus stracheyi, Poropuntius bantamensis, Scaphiodonichthys acanthopterus, Garra cambodgiensis, Balitora sp. 1, Balitora sp. 2, Homalopteroides cf. smithi, Glyptothorax cf. laosensis, Oreoglanis sp., Channa gachua, and Mastacembelus armatus, plus the congeners Schistura desmotes, S. poculi, S. spilota, and S. waltoni.

Some of its habitats are under threat by over-grazing, deforestation, deliberately-induced forest fires and collection for the aquarium trade. It’s thus considered endangered though populations currently remain healthy.

Maximum Standard Length

35 – 40 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 60 ∗ 30 cm or similar is sufficient.

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.

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 also be considered routine.

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.

Water Conditions

Temperature: 18 – 24 °C

pH: 7.0 – 8.5

Hardness: 90 – 268 ppm

Diet

Naturally a micropredator feeding on small insects, worms, crustaceans, and other zooplankton with only relatively small amounts of plant matter and other organic detritus consumed.

In the aquarium it’s easily-fed and 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, chopped bloodworm, etc., will result in the best colouration and condition.

Behaviour and CompatibilityTop ↑

Best maintained alone or alongside comparably-sized, peaceful fishes which inhabit similar biotopes in nature, especially those which swim in open water such as Microdevario, species. Do not keep it with territorial or otherwise competitive bottom-dwellers.

Though not gregarious in the sense of schooling or shoaling fishes it does seem to do best in the presence of conspecifics and provided plenty of cover is available any aggression should be minimal.

Sexual Dimorphism

None reported, though sexually mature females should appear rounder or thicker bodied when gravid.

Reproduction

Unreported.

NotesTop ↑

Despite its endangered status this species is available in the aquarium trade on a sporadic basis.

It can be told apart from other members of the genus by the following combination of characters: body with four black bars on a yellow base colour, usually forming saddles along the dorsal midline, and with a rounded yellow blotch on the mid-dorsal line within each saddle; body slender, its depth at dorsal-fin origin 11-16 % SL; no sexual dimorphism; no black bar at caudal-fin base; pelvic-fin origin in front of vertical through dorsal-fin origin.

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. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
2. 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).
3. Vidthayanon, C., 2003 - Ichthyological Exploration of Freshwaters 14(4): 307-310
   Schistura pridii, a new nemacheiline loach (Teleostei: Balitoridae) from Upper Chao Phraya drainage, northern Thailand.
4. 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.