Nemacheilus selangoricus DUNCKER, 1904

SynonymsTop ↑

Nemachilus selangoricus Duncker, 1904; Noemacheilus selangoricus (Duncker, 1904); Nemacheilus kuiperi de Beaufort, 1939; Noemacheilus translineatus (Fowler, 1939)

Etymology

Nemacheilus: from the Greek nēma, meaning ‘thread’ or ‘filament’ and cheilos, meaning ‘lip’ in reference to the furrowed lip in members of this genus.

selangoricus: named for the Malaysian state of Selangor.

Classification

Order: Cypriniformes Family: Nemacheilidae

Distribution

Type locality translates as ‘surroundings of Kuala Lumpur’, but current records suggest a range extending from Trang province, southern Thailand, throughout much of Peninsular Malaysia, Singapore, western Borneo (Malaysian states of Sabah and Sarawak, Brunei Darussalam, and Indonesian province of Kalimantan Barat), Belitung (aka Billiton) Island, and central-eastern Sumatra (Jambi province).

Habitat

Most commonly found in shallow (<1 m deep), flowing stretches of forest streams with substrates of sand, gravel, small rocks and organic detritus.

The water is generally clear to slightly tannin-stained and aquatic plants usually limited to the odd patch of Cryptocoryne spp. though riparian vegetation often grows thickly.

Maximum Standard Length

55 – 60 mm.

Aquarium SizeTop ↑

An aquarium with a base measuring 60 ∗ 30 cm or more is recommended.

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 – 25 °C

pH: 5.0 – 7.5

Hardness: 18 – 215 ppm

Diet

Nemacheilus 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 consumed, mostly via the stomach contents of prey items.

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.

Behaviour and CompatibilityTop ↑

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 rheophilic loaches from genera such as Gastromyzon, Pseudogastromyzon, Beaufortia, and Sewellia, plus benthic cyprinids like Crossocheilus and Garra species.

Some similarly-shaped relatives such as other Nemacheilus, Acanthocobitis, and Schistura spp. are excessively territorial or otherwise aggressive, although a combination may work in larger aquaria.

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.

Sexual Dimorphism

Mature males possess a suborbital flap, plus small tubercules on the upper side of pectoral-fin rays 1-4, and underside of pectoral-fin ray 2.

Adult females are likely to be slightly larger and heavier-bodied than males.

Reproduction

Unrecorded.

NotesTop ↑

This species is a member of the N. selangoricus group within the genus, an assemblage first recognised by Hadiaty and Kottelat (2009) and characterised by possession of two rows of horizontally-arranged, elongate scales on the caudal peduncle each with a tubercle at the posterior edge, which in some species is located at the tip of an acuminated process (long, tapering, posterior projection), plus body pattern consisting of dark, vertical bars.

Other species presently included in this group are N. spiniferus, N. tebo and N. tuberigum.

N. selangoricus is most similar to N. spiniferus since it possesses acuminate scales above and below the lateral line on the caudal peduncle, a feature not shared with any other congener. It can however be distinguished by the following characters: presence of 8-12 very regular dark bars on flanks (vs. 10-13 irregularly-shaped bars in N. spiniferus), 3-5 times wider than the interspaces, middle area of bars often lighter than the margin or as light as the base body colour, in which cases the bar appears split into two thinner bars; dorsal head length 18-22 % SL (vs. 21-23 %); process of acuminate scales shorter than (vs. as long as) remainder of scale, it’s base width approximately ¼-⅓“ of scale width (vs. about ½).

The rows of elongated scales on the caudal peduncle in N. tebo and N. tuberigum are not acuminate and lack the posterior process, plus the black spot at the base of the anterior dorsal-fin rays and rows of similarly-coloured markings in the dorsal-fin seen in N. selangoricus and N. spiniferus are also absent.

Following Kottelat (1990) the genus Nemacheilus is characterised by a combination of characters as follows: elongate body; complete lateral line; presence of enlarged scales above and below the lateral line in some species; caudal-fin forked to deeply forked with enlarged upper lobe; large eye; small, strongly arched mouth; lips usually thin; usually no median interruption in upper lip; upper jaw with processus dentiformis (a tooth-like projection); no median notch in lower jaw; long barbels; males usually with suborbital flap, pectoral-fin rays 2-6 thickened and with rows of tubercules.

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 Museum d'Histoire Naturelle 'Grigore Antipa' 35: 429-495
   A generical classification of Nemacheilinae with description of two new genera (Teleostei: Cypriniformes: Cobitidae).
2. Kottelat, M., 1984 - Japanese Journal of Ichthyology 31(3): 225-260
   Revision of the Indonesian and Malaysian loaches of the subfamily Noemacheilinae.
3. Kottelat, M., 1990 - Verlag Dr. Friedrich Pfeil, München, Germany: 1-262
   Indochinese nemacheilines. A revision of nemacheiline loaches (Pisces: Cypriniformes) of Thailand, Burma, Laos, Cambodia and southern Viet Nam.
4. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
5. Kottelat, M., 2013 - Raffles Bulletin of Zoology Supplement No. 27: 1-663
   The fishes of the inland waters of southeast Asia: a catalogue and core bibiography of the fishes known to occur in freshwaters, mangroves and estuaries.
6. Tan, H. H. and M. Kottelat, 2009 - Ichthyological Exploration of Freshwaters 20(1): 13-69
   The fishes of the Batang Hari drainage, Sumatra, with description of six new species.
7. 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).
8. Šlechtová, V., J. Bohlena 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.