Cyclocheilichthys heteronema (BLEEKER, 1854)

SynonymsTop ↑

Barbus heteronema Bleeker, 1854

Etymology

Cyclocheilichthys: from the Ancient Greek κύκλος (kýklos), meaning ‘circle’, χείλος (cheílos), meaning ‘lip’, and ἰχθύς (ikhthús), meaning ‘fish’, possibly in reference to the continuous lips in this genus.

heteronema: from the Ancient Greek ἕτερος (héteros), meaning ‘different’, and νῆμα (nêma), meaning ‘thread’, in reference to the branched, fimbriated barbels in this species.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

This species is currently understood to have a considerable natural range extending eastwards from Myanmar via Thailand, Laos, Cambodia as far as Vietnam and to the south through Peninsular Malaysia and into the Greater Sunda Islands of Borneo and Sumatra.

It thus occurs in the Mekong, Mae Klong and Chao Phraya drainages as well as a host of other river basins, lakes and reservoirs including the Tonlé Sap river and lake system in Cambodia. Despite this wide distribution it doesn’t appear to be common in nature with most of the existing records pertaining to Peninsular Malaysia.

Type locality is ‘Sambas, western Borneo, Indonesia’, which presumably refers to the settlement of the same name in Kalimantan Barat (West Kalimantan) province which lies on the lower Sambas Besar river.

Habitat

Little information is available but according to reports it predominantly inhabits deeper waters and can only be found in shallower zones for a few weeks each year. During the wet season it is known to move into inundated floodplains and forested areas.

Maximum Standard Length

100 – 120 mm.

Aquarium SizeTop ↑

An aquarium with base measurements of at least 120 ∗ 45 cm will be required for long-term care.

Maintenance

Prefers a dimly-lit environment and a soft, sandy substrate is recommended to allow natural feeding behaviour (see ‘Diet’). The addition of some good-sized pieces of driftwood will provide shady patches that will be appreciated. If you can’t find driftwood of the desired shape common beech or oak is safe to use if thoroughly dried and stripped of bark.

While many aquatic plants will fail to thrive in such conditions species such as Microsorum, Taxiphyllum or perhaps some potted Cryptocorynes spp. should survive. A few patches of floating vegetation would also help to further diffuse the light entering the tank and provide a more natural feel.

Water Conditions

Temperature: 21 – 26 °C

pH: 6.0 – 7.5

Hardness: 18 – 268 ppm

Diet

Apparently a micropredator grazing the substrate and other surfaces for small items including insects, crustaceans and worms. For it to develop the best condition in the aquarium offer daily meals of small live and frozen foods such as chironomid larvae (bloodworm), Tubifex, Daphnia and Artemia alongside good quality, sinking prepared foods.

Behaviour and CompatibilityTop ↑

This species is very peaceful indeed but tankmates must be chosen with care as it has a somewhat retiring nature and may be intimidated or outcompeted for food by larger/more boisterous tankmates. UK aquarist Mick Wright maintained a group and achieved success keeping them alongside small, peaceful cyprinids including Pethia phutunio, P. gelius plus loaches from the genera Yunnanilus and Nemacheilus.

A community based around one of its native countries or river basins could also make a worthwhile project with some interesting alternatives. For example in Lake Tonlé Sap sympatric species include Rasbora daniconius, R. rubrodorsalis, Nemacheilus pallidus, Parambassis siamensis, Trichogaster microlepis and T. trichopterus.

It’s a gregarious fish by nature and ideally should be kept in a group of at least four to get the best out of it in the aquarium; the fish should be less nervous in the presence of conspecifics.

Sexual Dimorphism

Sexually mature females are likely to be rounder in the belly than males.

Reproduction

Not thought to have been bred in aquaria to date.

NotesTop ↑

C. heteronema is easily distinguished from its congeners as it possesses unique, fimbriated barbels which are extended downwards when the fish is browsing for food items. As with others in the genus little has been written regarding its captive care but it makes a peaceful and unusual addition to larger aquaria.

The best way of obtaining some may be to keep an eye on shipments of other wild fish from Indochina and the Greater Sunda Islands as it’s rarely, if ever, imported in numbers but may appear as bycatch from time-to-time.

Members of Cyclocheilichthys are characterised by possessing a serrated dorsal fin spine, 9 branched pelvic fin rays, a conical snout, small, subterminal mouth and parallel rows of sensory folds on the snout and cheeks. The latter feature is lacking in most other cyprinids but present in a few genera including Eirmotus, Oreichthys, and Neobarynotus.

There have been some nomenclatural issues in recent years, ostensibly because Cyclocheilichthys and the now synonymous Anematichthys were used simultaneously by Bleeker (1859) in reference to the same fish, C. apogon. The issue was addressed by Kottelat (1999) but later misinterpreted by Pasco-Viel, Veran and Variot, 2012, who concluded that Cyclocheilichthys represents a paraphyletic grouping and split the genus into two groups: Cyclocheilichthys (comprising C. enoplos) and Anematichthys (comprising C. apogon, C. armatus and C. repasson).

This was corrected by Kottelat (2013), and Cyclocheilichthys currently comprises seven species with the revalidated genus Cyclocheilos including the former members C. enoplos and C. furcatus. C. heteronema differs considerably from other Cyclocheilichthys species and may eventually be separated with the generic name Oxybarbus available for it.

Given the extremely wide range exhibited by C. heteronema, and taking into account patterns observed in other Southeast Asian fishes, it seems logical that this species may also turn out to represent a group of closely-related taxa.

References

1. Cervancia, M. and M. Kottelat, 2007 - Raffles Bulletin of Zoology 55(1): 141-145
   Cyclocheilichthys schoppeae, a new species of freshwater fish (Teleostei: Cyprinidae) from northern Palawan, Philippines.
2. Doi, A. and Y. Taki, 1994 - Japanese Journal of Ichthyology 41(1): 84-85
   First record of the cyprinid, Cyclocheilichthys heteronema, from Lake Tonle Sap of the Mekong River System.
3. Kottelat, M., 2001 - WHT Publications, Colombo: 1-198
   Fishes of Laos.
4. Kottelat, M., 2013a - Zootaxa 3640(4): 479-482
   The valid generic names for the fish species usually placed in Cyclocheilichthys (Pisces: Cyprinidae).
5. Kottelat, M., 2013b - Raffles Bulletin of Zoology Supplement 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. Kottelat, M. and E. Widjanarti, 2005 - Raffles Bulletin of Zoology Supplement 13: 139-173
   The fishes of Danau Sentarum National Park and the Kapuas Lakes area, Kalimantan Barat, Indonesia.
7. Pasco-Viel, E., M. Veran and L. Variot , 2012 - Zootaxa 3586: 41-54
   Bleeker was right: Revision of the genus Cyclocheilichthys (Bleeker 1859) and resurrection of the genus Anematichthys (Bleeker 1859), based on morphological and molecular data of Southeast Asian Cyprininae (Teleostei, Cypriniformes).
8. Pasco-Viel, E., M. Veran and L. Variot , 2013 - Zootaxa 3640(3): 483-484
   Comments on 'The valid generic names for the fish species usually placed in Cyclocheilichthys' (KOTTELAT 2013) and a correction of Pasco-viel et al. (2012).
9. Rainboth, W. J., 1996 - FAO, Rome: 1-265
   Fishes of the Cambodian Mekong. FAO Species Identification Field Guide for Fishery Purposes.