'Nemacheilus' anguilla ANNANDALE, 1919

SynonymsTop ↑

Nemachilus anguilla Annandale, 1919; Noemacheilus anguilla (Annandale, 1919); Nemachilus poonaensis Menon 1950; Nemacheilus poonaensis Menon 1950

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.

Classification

Order: Cypriniformes Family: Nemacheilidae

Distribution

Endemic to the Western Ghats range of mountains, southwestern India. It was described from ‘Yenna River at Medha, Satara District, Maharashtra (Mumbai Presidency), India’, but has subsequently been recorded from numerous river drainages in the states of Maharashtra, Karnataka, and Kerala.

These include the Mula-Mutha River in Maharahstra, Sharavathi, Bhadra and Kali rivers in Karnataka and Pampa river in Kerala.

In addition, N. poonaensis (Menon 1950) was described from the Anshi and Gangawali rivers in Karnataka but is currently considered a junior synonym of N. anguilla.

Habitat

Inhabits well-oxygenated, moderate to fast-flowing rivers and streams with substrates of gravel, cobbles, larger boulders and exposed bedrock.

Many habitats are being polluted by domestic and industrial waste or degraded by introduction of exotic species and large-scale sand mining operations.

In the Tunga river sympatric species include Barilius  bakerii, Devario malabaricus, Danio  rerio, Rasbora daniconius, Dawkinsia arulius, D. assimilis, Haludaria fasciata, Pethia ticto, Puntius sahyadriensis, ‘Puntius‘  narayani, Systomus sarana, Tor kudree, Garra  mullya, Psilorhynchus tenura, Schistura  nilgiriensis, S.  semiarmatus, S.  denisonii, Aplocheilus blockii, A.  lineatus, Pristolepis marginata, and Channa gachua.

Maximum Standard Length

45 – 50 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: 6.0 – 7.5

Hardness: 18 – 179 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.

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

When in spawning condition males exhibit a bright red snout, red distal margins in the upper and lower caudal-fin lobes, and overall body patterning darkens, while females possess a noticeably-rounded abdomen and paler colour pattern.

Reproduction

This species has spawned in the aquarium of Indian aquarist Deepak Sathya.

Courtship was led by the male and the eggs apparently released in midwater, near the outlet of the filter.

Due to the presence of other fishes (Barilius, Schistura and Botia species) no fry survived in the main display, but a number were raised by uncoupling the external filter unit, collecting the water and detritus from inside and placing these in a separate container.

Free-swimming fry could be seen after 6-7 days and were initially fed on rotifers. When the adults spawned pH was 7.2 and water temperature around 21°C, the latter having dropped suddenly prior to an incoming storm and possibly triggering nuptial behaviour.

NotesTop ↑

‘N.‘ anguilla can be told apart from other Indian members of the genus by possessing dark flank markings which are partially or completely merged to form a lateral stripe, and an almost-complete lateral line extending to the anal-fin.

Kottelat (2012) states that its generic placement requires additional study hence the genus name is currently written ‘Nemacheilus‘.

In the similar-looking ‘N.‘ stigmofasciatus there are 6-7 clearly-separated, brownish blotches along the flanks, and the lateral line is incomplete, extending to the pectoral fins, while in ‘N.‘ monilis the flank markings appear as a moniliform stripe running from snout to caudal-fin base and the lateral line is complete, extending to the caudal-fin.

In addition to the dark lateral markings Nemacheilus species from southwestern India also possess a short dorsal-fin compared with most other members of the genus, with 7-8 branched rays, plus relatively large eyes.

Following Kottelat (1990) 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. Annandale, N., 1919 - Records of the Indian Museum (Calcutta) v. 16 (pt 1): 125-138
   The fauna of certain small streams in the Bombay Presidency. v. Notes on freshwater fish mostly from the Satara and Poona districts.
2. Arunachalam, M. and M. Muralidharan, 2009 - Journal of Threatened Taxa 1(3): 147-150
   Nemacheilus stigmofasciatus, a new species of nemacheiline loach (Cypriniformes: Balitoridae) from the Western Ghats, India.
3. Arunachalam, M. and M. Muralidharan, 2007 - Zoos' Print Journal 22(6): 2724-2725
   Note on the validity of the identifying character of a rare loach Nemacheilus monilis Hora.
4. 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).
5. 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.
6. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).