Paracanthocobitis pictilis (KOTTELAT, 2012)

Cherry-fin Loach

SynonymsTop ↑

Acanthocobitis pictilis Kottelat, 2012

Etymology

Paracanthocobitis: from the Greek παρά (para), meaning ‘close beside,’ and the genus Acanthocobitis from the Greek ἄκανθος ‎(ákanthos), meaning ‘thorned’, in reference to the spine beneath the eye in the type species A. longipinnis, and κωβιός ‎(kōbiós), meaning ‘a kind of small fish’.

pictilis: from the Latin pictilis, meaning ’embroided’, and presumably in reference to this species’ colour pattern.

Classification

Order: Cypriniformes Family: Nemacheilidae

Distribution

Kottelat (2012a) has this species occurring in the Ataran River, an affluent of the upper Salween basin flowing into Myanmar from Kanchanaburi province, Thailand, and the Mae Khlong watershed in western Thailand.  Singer & Page (2015) restrict it to the Ataran River, and describe the Mae Khlong population as a new distinct species, Paracanthocobitis maekhlongensis Singer and Page, 2015.

Type locality is given as “stream ‘Chon Son’ between Kyondaw and Phadaw, about 20 km northwest of Payathouzu at border with Thailand near Chedi Sam Ong, Three Pagoda Pass”.

Occurrences of ‘P. rubidipinnis‘ from the Hanthayaw River, another Salween tributary originating in Tak province, Thailand, before entering Myanmar presumably pertain to P. pictilis as well.  Singer & Page (2015) restrict P. rubidipinnis to the Irrawaddy basin in Myanmar.

In Thailand the Ataran and Hanthayaw are known as the Kasat and Suriya, and located in the Thung Yai Naresuan and Huai Kha Khaeng wildlife sanctuaries, respectively.

Habitat

Inhabits shady, fast-flowing stretches and riffles and also found in deeper pools at times. Favoured habitats are well-oxygenated with clear water, a substrate comprising sand, gravel, rocks, boulders and patches of leaf litter with a rich biofilm normally carpeting solid surfaces.

Submerged driftwood and the roots of marginal vegetation are also typical features, while aquatic plants such as Cryptocoryne crispatula var. balansae and Pogostemon helferi grow in stiller parts of these well-oxygenated habitats.

Other fish species occuring in the Ataran and Hanthayaw, and which may occur sympatrically, include Parambassis pulcinella, Botia kubotai, Schistura maepaiensis, Homalopteroides modestus, Syncrossus berdmorei, Pangio fusca, Pethia stoliczkana, Microdevario kubotai, Crossocheilus burmanicus, Akysis vespa, Glyptothorax dorsalis, Amblyceps caecutiens, Batasio feruminatus, B. dayi, Caelatoglanis zonatus, Psilorhynchus robustus and Tetraodon cutcutia.

Maximum Standard Length

80 – 91 mm.

Aquarium SizeTop ↑

Base dimensions in excess of 90 ∗ 30 cm are suggested.

Maintenance

Should not prove difficult to maintain under the correct conditions meaning we recommend designing the aquarium to resemble a flowing stream or river with a substrate of variably-sized rocks, sand, fine gravel and some large water-worn boulders.

This can be further furnished with driftwood branches arranged to form a network of nooks, crannies and shaded spots. While the majority of aquatic plants will fail to thrive in such surroundings hardy genera such as Microsorum, Bolbitis or Anubias spp. can be grown attached to the décor.

Like many fishes that naturally inhabit running waters it’s likely to be intolerant of accumulated organic waste and require spotless water at all times in order to thrive.

Such species also do best if there is a high level of dissolved oxygen and a decent level of water movement in the tank so external filters, powerheads, airstones, etc., should be employed in order to obtain the desired effect.

As stable water conditions are obligatory for its well-being this fish should never be added to biologically-immature aquaria.

Water Conditions

Temperature: 21 – 26 °C

pH: 6.5 – 7.5

Hardness: 18 – 143 ppm

Diet

Probably a micropredator feeding on insect larvae and suchlike in nature.  Singer and Page (2015) report that stomach contents examined during their study were larval chironomids and ephemeropterans.

In the aquarium it will accept sinking dried foods but should also be offered regular meals of small live and frozen fare such as Daphnia, Artemia, bloodworm, etc. A varied diet is the key to maintaining it in the best of health.

Behaviour and CompatibilityTop ↑

Apparently not as peaceful as other members of the genus and very bold so best kept with similarly-sized, active, schooling or shoaling cyprinids.

Other robust loaches from genera such as Schistura, Nemacheilus, Botia, and Yasuhikotakia also make suitable tankmates as do many Garra species.

There exist reports of some male specimens becoming excessively territorial or aggressive when maintained individually or in small numbers so a mixed-sex group of at least six is best. This should allow subdominant individuals some respite while ensuring males spend more time interacting with conspecifics than molesting tankmates.

Sexual Dimorphism

Males possess a deep suborbital slit visible as a cleft in the skin extending from the the lower margin of the eye to the base of the posterior rostral barbel, the dorsal surface of the first 5-6 pectoral-fin rays is thickened with a dense covering of small tubercules, and there are patches of unculi on the opercle and suborbital area.

Females lack these features althouh a shallow groove is visible beneath the eye in some specimens. In nuptial males the snout and fins are suffused with reddish pigmentation while gravid females are deeper-bodied.

Reproduction

Unrecorded.

NotesTop ↑

Prior to description this species was considered to represent, and traded as, Acanthocobitis [subsequently Paranthacobitis] rubidipinnis, but that species is apparently endemic to the lower Irrawaddy basin in Myanmar and unknown in the aquarium hobby.

Paracanthocobitis pictilis can be distinguished from all other species of Paracanthocobitis by the combination of suborbital groove in male; no large dark spots, blotches or bars along side of body; 8–11 dark bands on caudal fin; small vertical or crescent-shaped black caudal blotch near dorsal margin of caudal peduncle; 12 and 1/2 to 13 and 1/2 branched dorsal-fin rays; 8 pelvic-fin rays.

Paracanthocobitis pictilis differs from all other species in the genus in lacking conspicuous large dark spots, blotches or bars along side of body, and from all species except P. canicula, P. maekhlongensis, and P. mandalayensis in having a suborbital groove (vs. suborbital flap) in males. It further differs from P. maekhlongensis in having a vertical or crescent-shaped (vs. round) black caudal spot, from P. mandalayensis in having 12 and 1/2 to 13 and 1/2 (vs. 10 and 1/2 to 11 and 1/2) branched dorsal-fin rays, and from P. canicula in having a vertical or crescent-shaped (vs. round) black caudal spot and 8–11 (vs. 5–7) dark bands on the caudal fin.

P. rubidipinnis differs from P. pictilis in possession of 13½ to 15½ (usually 14½) branched dorsal-fin rays, a suborbital flap in males, and colour pattern comprising a series of blackish, vertically-elongated blotches on the lateral line with brown saddles on the dorsal surface which may or may not be connected to the lateral markings.

The genus Acanthocobitis was described by Peters (1861) with Acanthocobitis longipinnis designated as the type species.  The placement and status of this species was questioned by several authors beginning with Menon (1987) who considered it a junior synonym of Cobitis botia Hamilton, 1822.  Grant (2007) compared the holotype of A. longipinnis with live specimens of A. botia and found the two species to be easily distinguished.  He noted that A. longipinnis is distinguished from all other Acanthocobitis species in having a pointed caudal fin, vertically oriented suborbital flap, slender body, long dorsal fin, anus closer to anal-fin insertion than to pelvic-fin insertion, and greenish colouration.

Grant (2007) considered Acanthocobitis longipinnis to be a junior synonym of A. pavonacea and proposed the subgenus Paracanthocobitis (type species C. zonalternans) to include all other species since he regarded A. pavonacea to be taxonomically unique.  Kottelat (2012a) remarked that the identity of A. longipinnis required verification and later (Kottelat, 2012b) classed Paracanthocobitis as a questionable synonym of Acanthocobitis.

Singer and Page (2015) recognize Paracanthocobitis as a genus, differing from Acanthocobitis as diagnosed by Grant (2007, 2008), although the two genera are most likely sister taxa based on the unique papillated pad on either side of a medial interruption on the lower lip.  Fourteen species including five new species described therein are assigned to Paracanthocobitis, with Acanthocobitis treated as monotypic, containing only A. pavonacea, a species restricted to the Brahmaputra and Ganges river basins of northern India and Bangladesh.  Acanthocobitis longipinnis is considered to be a synonym of A. pavonacea (Grant, 2007); however, the only available specimen of A. longpinnis is the poorly preserved holotype.  Collection of fresh material may show the two forms to be distinguishable from one another.  [Singer and Page, 2015, p. 398]

Paracanthocobitis is distinguished from all other genera in the family by the combination of lower lip with a large papillated pad on either side of a medial interruption; upper lip with 2–5 rows of papillae and continuous with lower lip; conspicuous black spot with white outline (an ocellus) on upper half of caudal-fin base.

Paracanthocobitis is distinguished from Acanthocobitis in having an emarginate or truncate (vs. pointed) caudal fin; 9 and 1/2 –15 and 1/2 (vs. 17 and 1/2 –19 and 1/2) branched dorsal-fin rays; rounded (vs. more triangular-shaped) head in lateral view; horizontally (vs. vertically) oriented suborbital flap or groove; papillated pad on either side of narrow (vs. wide) medial interruption in lower lip; anus closer to pelvic-fin insertion than to anal-fin insertion (vs. closer to anal-fin insertion).  [Singer and Page, 2015, p. 380]

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. Kottelat, M., 2012a - Zootaxa 3327: 45-52
   Acanthocobitis pictilis, a new species of loach from Myanmar and Thailand (Teleostei: Nemacheilidae).
2. Grant, S., 2007 - Ichthyofile No. 2: 1-9
   A new subgenus of Acanthocobitis Peters, 1861 (Teleostei: Nemacheilidae).
3. Grant, S., 2008 - BSSW-Report 20(3): 49-52
   Schmerlen der Gattung Acanthocobitis Peters, 1861.
4. 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.
5. Kottelat, M., 2012b - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
6. 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.
7. Singer, R. A. and L. M. Page, 2015 - Copeia v. 103 (no 2): 378-401
   Revision of the zipper loaches, Acanthocobitis and Paracanthocobitis (Teleostei: Nemacheilidae), with descriptions of five new species.
8. 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).