Schistura sp. 1

Ring Loach

Etymology

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

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Unclear, but fish for the aquarium trade are collected in the Torsa river near Cooch Behar in northern West Bengal state, India.

The Torsa is a tributary of the Brahamaputra system arising in China and flowing through Bhutan and West Bengal before entering the Brahamaputra in Bangladesh.

Habitat

Unconfirmed but would appear to dwell over sand or other soft substrate-types in nature since it has a propensity to bury itself when startled.

Aquarium SizeTop ↑

Even a small group will need an aquarium with base dimensions of 75 ∗ 30 cm or similar.

Maintenance

Not difficult to maintain under the correct conditions. At least part of the substrate should be composed of sand to allow the fish to bury themselves and thus display their natural threat response.

This can be further furnished with smooth rocks and driftwood branches arranged to form a network of nooks, crannies, and shaded spots.

Aquatic plants can also be added with genera such as Microsorum, Bolbitis, or Anubias spp. particularly useful since they 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.

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: 18 – 24 °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.

Behaviour and CompatibilityTop ↑

Unlike many congeners this species is peaceful with conspecifics and seems to appreciate being maintained in a group so the purchase of four or more specimens is highly recommended.

In terms of tankmates fishes which inhabit similar biotopes in nature constitute the best options, especially peaceful, open water-dwelling cyprinids since the presence of one or two schools can make a visible difference to the confidence of this naturally reclusive loach.

Other possibilities include sand-dwelling loaches such as Acanthopsoides or Canthophrys species.

Some similarly-shaped relatives, including many Schistura spp., are excessively territorial or otherwise aggressive, although a well-chosen combination may work in larger aquaria.

Reproduction

Unreported.

NotesTop ↑

The identity of this fish is somewhat unclear although it’s available in the aquarium trade on an occasional basis.

It’s been considered to represent various species including Schistura beavani, S. montana and S. himachalensis but there exist arguments to suggest it might not be any of these.

For example, according to Günther’s description S. beavani has 9 vertical bars on the body and blackish spots on the rays of the dorsal and caudal fins, while S. sp. 1 appears to possess a minimum of 11 vertical bars and lacks markings in the fins.

S. montana is described as having 12 bars which are wider than the interspaces between them and a single row of spots in the dorsal and caudal fins, whereas in S. sp. 1. the interspaces are significantly wider than the bars.

In addition, S. montana and S. himachalensis were both described from the Indus river drainage in Himachal Pradesh state, northern India and may not occur in the Brahmaputra system which lies well over 1000 km away, although S. himachalensis has been recorded in Nepal.

S. sp. 1 also displays some morphological and behavioural peculiarities which set it apart from the majority of congeners, so there seems a reasonable chance it hasn’t been identified yet.

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. Bănărescu, P. M. and T. T. Nalbant, 1995 - Travaux du Muséum d'Histoire Naturelle : 429-495
   A generical classification of Nemacheilinae with description of two new genera (Teleostei: Cypriniformes: Cobitidae).
2. Conway, K. W., D. R. Edds, J. Shrestha and R. L. Mayden, 2011 - Journal of Fish Biology 79(7): 1746-1759
   A new species of gravel-dwelling loach (Ostariophysi: Nemacheilidae) from the Nepalese Himalayan foothills.
3. Günther, A., 1868 - Catalogue of the fishes in the British Museum v. 7: i-xx + 1-512
   Catalogue of the Physostomi, containing the families Heteropygii, Cyprinidae, Gonorhynchidae, Hyodontidae, Osteoglossidae, Clupeidae,... [thru]... Halosauridae, in the collection of the British Museum.
4. 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.
5. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
6. 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).
7. 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.