Schistura kengtungensis

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

kengtungensis: named for Keng Tung, a town close to the type locality.

This species is distributed in the middle Mekong River basin in north and northeastern Thailand, Myanmar and Xishuangbanna Dai Autonomous Prefecture, Yunnan province, southern China, and is also known from the Nam Beng, Nam Tha and Nam Yuoan drainages in Laos.

Type locality is 'Laun We (Loi Mwe, 21°10'N, 99°45'E), Keng Tung, Mekong basin, Myanmar, elevation 5600 feet'.

Specimens from China exhibit various morphological differences compared with those from Thailand and Myanmar (see 'Notes').

Inhabits shallow, narrow branches of streams with substrates of gravel or stone.

The Nam Mae Mao is a a fast-flowing, cascading mountain stream within the Mekong watershed in Chiang Mai province, northern Thailand. The substrate is composed of rocks and boulders and the habitat measures just 1-2 metres in width with a maximum depth of 40 cm16 in.

Sympatric species included the congener Schistura poculi plus Lepidocephalichthys berdmorei, Devario laoensis, Barilius sp. and Rhinogobius mekongensis.

Base dimensions of 90 ∗ 30 cm36 ∗ 12 in or equivalent should be the smallest considered.

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.

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.

Aquarium behaviour is currently unknown though it certainly appears to be a robust fish and we wouldn't recommend combining it with slow-moving, long-finned, or very placid tankmates.

Sexually mature females should be deeper-bodied than males.

Unrecorded.

This species may not yet have appeared in the aquarium trade.

It can be told apart from congeners by the following combination of characters as per Kottelat (1990, 2001): dorsal-fin origin above or slightly posterior to pelvic-fin origin; upper lip without notch or small median notch; cheeks inflated in adults larger than 55 mm2.2 in SL; head length fits 4.1-4.2 times in SL; body depth fits 6.1-6.2 times in SL; caudal peduncle length fits 5.5-6.0 times in SL; caudal peduncle depth fits 7.3-8.2 times in SL and 1.3-1.4 times in caudal peduncle length; body with 9-13 vertical bars measuring as wide as or wider than the interspaces between, bars sometimes incomplete or interrupted with those anterior to the dorsal-fin wider than those posterior to it and not always well-contrasted; dark bar at base of the caudal peduncle slightly curved and not reaching the dorsal and ventral midlines; anterior base of dorsal-fin with a black spot, followed by an orange patch and an elongate grey blotch.

Specimens from Yunnan examined by Chen et al. (2005) differed from the above in the following characters: snout pointed and depressed (vs. rounded and blunt in Kottelat's redescription); pelvic-fin reaching anus (vs. not reaching anus); black caudal peduncle bar widest at the midlateral point (vs. wider dorsally and ventrally).

In addition, Kottelat (1990) had noted that in some specimens the body bars are not well-contrasted on the flanks and are replaced by up to 8 longitudinally-elongate blotches, and the body is speckled with dark brown spots. Chen et al. (2005) did not observe such variability.

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 mm2.0 in 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.