Schistura sp. 4

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

Unknown. The specimens in our images were collected in the Siwalik hills around Darjeeling, West Bengal state, northern India.

The fish were collected from the habitat in our images, which appears to be a small hill stream with shallow, clear water and well-developed riparian vegetation. It is located well over 1000 m AMSL.

Minimum base dimensions of 120 ∗ 30 cm48 ∗ 12 in or similar are likely to be required for long-term care.

Likely to fare best 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.

Use a powerful external filter, additional powerhead(s), or airstone(s) to achieve the desired flow rate and oxygenation, and carry out weekly water changes of 30-50 % aquarium volume.

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., should 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.

This species has been collected for the aquarium hobby, albeit in small numbers at time of writing, but its identity is unclear.

Though obtained from close to the type locality of S. multifasciata (Day, 1878)[5], it does not seem to match the description of that species in which Day states that the vertical bars are numerous in the anterior portion of the body with 'about 5' bars posterior to the dorsal-fin.

Subsequent authors have referred to it as possessing 18-30 vertical bars, which the fish pictured here clearly does not have.

Another possibility may be Nemachilus rupecula var. inglisi Hora, 1935 which was described from Darjeeling and is currently considered a synonym of Schistura rupecola, but we've yet to see its description.

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.