Schistura aizawlensis LALRAMLIANA, 2012

Etymology

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

aizlawensis: named for Aizawl, the capital city of Mizoram state, India, where the type locality of the species is located.

Classification

Nemacheilidae

Distribution

Type locality is ‘India: Mizoram: Muthi River, a tributary of Tuirial River in vicinity of Zemabawk, Aizawl, 23°44′ 54″ N 92°45’27” E’, and to date this species is known only from the Muthi system.

The Muthi is an affluent of the Tuirial River which is itself a tributary of the Barak watershed. The Barak is one of the great rivers of southern Assam state, northern India, and forms part of the Surma-Meghna River System.

Habitat

The type series was collected from a moderate to strongly-flowing stream with a substrate of gravel and rocks and a water temperature of 22-28°C/71.6-82.4°F over the course of the day.

Sympatric fishes included unidentified Garra, Psilorhynchus and Glyptothorax spp.

Maximum Standard Length

The largest specimen in the type series measured 48.9 mm.

Aquarium SizeTop ↑

Minimum base dimensions of 80 ∗ 30 cm or equivalent should prove 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.

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 – 28 °C

pH: 6.0 – 7.5

Hardness: 36 – 215 ppm

Diet

Likely to feed 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 will accept dried foods of a suitable size but should not be fed these exclusively, and daily meals of small live and frozen fare such as Daphnia, Artemia, bloodworm, etc., will result in the best colouration and condition.

Sexual Dimorphism

Males possess a prominent suborbital flap which is absent in females.

Reproduction

Unrecorded.

NotesTop ↑

S. aizawlensis has been collected for the aquarium hobby although we’re unsure of its trade name.

It can be told apart from congeners by the following combination of characters: presence of 5-7 broad vertical bars on flanks in adults; sub-dorsal and postdorsal bars narrower than interspaces; pre-dorsal bars wider or equal to interspaces; all bars extending beneath lateral line ventrally; an orange patch between the last bar and the caudal-fin base, usually in the upper half; intestine without a loop but slightly bent behind the stomach; males with sub-orbital flap.

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. Lalramliana, 2012 - Ichthyological Exploration of Freshwaters 23(2): 97-104
   Schistura aizawlensis, a new species of loach from Mizoram, northeastern India (Cypriniformes: Balitoridae).
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. 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).
5. 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.