Pangio shelfordii (POPTA, 1903)

SynonymsTop ↑

Acanthophthalmus shelfordii Popta, 1903

Classification

Order: Cypriniformes Family: Cobitidae

Distribution

Current distribution is accepted to include the states of Terengganu, Pahang and Johor, Peninsular Malaysia and Singapore, plus the Great Sunda Islands of Sumatra and Borneo.

On Sumatra it’s known from the provinces of Riau, Jambi (Batang Hari River drainage) and Bangka Island.

In Borneo it occurs in the Malaysian state of Sarawak plus the Indonesian provinces of Kalimantan Barat (Kapuas River) and Kalimantan Timur (Mahakam River) meaning it’s also likely to occur in Kalimantan Tengah, which lies in between the former two.

Type locality is the Sarawak River near the city of Kuching, Sarawak but the habitat was reported to be under extreme pressure from human activity as long ago as the early 1990s when Kottelat and Lim (1993) failed to recollect the species there.

Habitat

Most commonly found in shallow, slow-moving sections of forest streams or other calm habitats such as swamps, oxbows, and backwaters.

Many such environments are associated with ancient peat swamps and contain black water although it’s also found in clear waters which may or may not be tannin-stained to some extent.

Such habitats are typically shaded from the sun by marginal vegetation and the dense tree canopy above.

The water generally has a negligible dissolved mineral content, is poorly buffered and pH can be as low as 3.0 or 4.0 due to the gradual release of tannins and organic acids from decaying plant material.

Depending on locality the substrate may be composed of peat, mud or sand with the fish typically abundant in piles of leaf litter.

In the Kapuas basin, Kalimantan Barat (West Kalimanatan), Indonesian Borneo P. shelfordii coexists with numerous species including Pangio semicincta, P. malayana, P. angullaris, Eirmotus insignis, ‘Puntius‘ anchisporus, ‘P.‘ hexazona, and Brachygobius xanthomelas.

Maximum Standard Length

70 – 80 mm.

Aquarium SizeTop ↑

An aquarium with base measurements of at least 60 ∗ 30 cm or equivalent is recommended.

Maintenance

Use a soft, sandy substrate since this species likes to dig and tends to spend some of its time completely buried. When coarser gravel is used it may become stressed or damage itself, and feeding behaviour can be inhibited.

A few driftwood roots and branches, placed in such a way that plenty of shady spots are formed, can be used to add structure to the display and addition of dried leaf litter would provide additional cover and aid in simulating natural conditions.

Fairly dim lighting is also preferable and aquatic plants from genera such as Microsorum, Taxiphyllum, and Cryptocoryne spp. can also be added.

Gentle filtration providing a little surface agitation is adequate and high flow rates best avoided. Ensure that small specimens are unable to enter filter intakes and cover the tank well as most loaches do jump at times, especially when introduced to a new environment.

Water Conditions

Temperature: 21 – 26 °C

pH: 4.0 – 7.0

Hardness: 0 – 143 ppm

Diet

Chiefly a micropredator sifting mouthfuls of substrate through the mouth and gills from which insect larvae, small crustaceans and suchlike are extracted with a proportion of the natural diet also likely to comprise organic detritus and plant material from the gut contents of prey.

In the aquarium it will accept sinking dried foods but should also be offered regular meals of live and frozen Daphnia, Artemia, bloodworm, micro worm, grindal worm, etc.

Behaviour and CompatibilityTop ↑

Pangio spp. are peaceful both with one another and other fishes and there exist no reports of them harming tankmates though they may prey on eggs or fry.

In nature they’re often found in large aggregations and in captivity will often pack themselves into a single nook, cranny or cave when at rest, so a group of at least 5-6 specimens should be the minimum purchased.

Small, peaceful species from similar environments such as Boraras, Sundadanio, smaller Rasbora, Trichopsis, Sphaerichthys, Kottelatlimia, etc., constitute the best tankmates.

Some sand-dwelling loaches from the family Nemacheilidae are also suitable but proper research is essential as some can be excessively competitive, territorial or otherwise aggressive.

Sexual Dimorphism

Adult females are typically heavier-bodied and a little larger then males, while in mature males the first pectoral-fin ray is visibly branched and thickened.

Reproduction

Unrecorded in aquaria but presumably a seasonal spawner in nature.

NotesTop ↑

This species is exported occasionally, often as bycatch among shipments of congeners.

It’s included in the P. shelfordii group of closely-related species and can be distinguished from other members by the following combination of characters: body with a more-or-less conspicuous series of midlateral blotches, sometimes forming a solid lateral stripe; a dark bar-like marking at the base of the caudal-fin; caudal-fin mottled; three dark bars on head (not including snout markings); median lobe of lower lip forming a barbel; 46-51 vertebrae.

Patterning is highly variable depending both within and between populations and as currently understood the species represents an assemblage containing a number of unidentified taxa (Kottelat and Lim, 1993; Tan and Kottelat, 2009; Bohlen et al., 2011; Kottelat, 2012).

For example, those from Singapore and Johor possessing intricate mottling on the dorsal surface while individuals from Terengganu have a series of saddle-like markings either alternating or connecting with the midlateral markings. The former may actually be Pangio muraeniformis (de Beaufort 1933) although we’ve been unable to confirm this as yet.

Sarawak specimens have a similar pattern to those from Terengganu but the midlateral markings tend to be extended vertically and considerably darker at mid-body, with the dorsal saddles much lighter and tending to adjoin each other leaving only thin pale patches between. The species was described from the Sungai (river) Sarawak close to the city of Kuching.

In fish from Bangka Island the midlateral blotches form a continuous dark stripe with irregular markings with dorsal patterning consisting of either poorly-defined predorsal saddles or fine spots.

In those from the upper Kapuas River, Kalimantan Barat, Borneo, possess irregular midlateral markings which are darker at midbody height and relatively few, irregularly-shaped, diffuse dorsal saddles.

In the lower Kapuas populations have a speckled body patterning with a black midlateral stripe and dorsal saddles in just the occasional specimen.

Some Sumatran and Bornean populations of P. shelfordii superficially resemble P. piperata which can cause issues with identification as the two often occur together.

In general however the body patterning in P. piperata is much plainer than that of P. shelfordii, and they differ in vertebral counts (mode 47 vs. 50, respectively).

The pectoral fins in male P. piperata are also proportionally longer being approximately twice as long as those in females vs. slightly longer in P. shelfordii.

Kottelat and Lim (1993) suggested that the P. shelfordii group represents one of four such assemblages within the genus alongside the P. anguillaris, P. kuhlii and P. oblonga groups.

This unofficial system was followed until Bohlen et al. (2011) published a molecular phylogenetic analysis including 18 recognised species plus a number of undescribed ones.

Their results suggest the existence of three, rather than four, major lineages within the genus; the P. anguillaris and P. shelfordii groups represent two of them with Kottelat and Lim’s P. kuhlii and P. oblonga groups together forming the third.

P. shelfordii group members are separated from those of the P. kuhlii-oblonga and P. anguillaris groups by possession of a pair of labial ‘barbels’ on the lower lip, a dark bar at the base of the caudal-fin, several rows of spots on the caudal-fin and a relatively slim caudal peduncle.

They currently include P. atactos, P. incognito, P. muraeniformis, P. piperata, P. shelfordii and P. superba.

Pangio is among the most speciose cobitid genera and widespread throughout South and Southeast Asia with species diversity thought to be considerably greater than currently recognised.

Pangio species are often generically referred to as ‘kuhli’ or ‘coolie’ loaches in the aquarium hobby, the latter a variation of the former which was itself derived from the surname of German naturalist Heinrich Kuhl (1797-1821). Ichthyologists tend to refer to them as ‘eel loaches’.

They’re distinguished from other cobitids by their long, slender body shape, relatively high number of vertebrae and the position of the dorsal-fin which is situated well behind the origin of the pelvic fins (vs. in front of, above or only slightly behind).

Several described members were previously included in the genus Acanthophthalmus which Kottelat (1987) demonstrated to be a syonym of Cobitis, and he chose the replacement name Pangio in preference to its simultaneous synonym Apua (Blyth, 1860).

Myers (1929) placed P. anguillaris as type species of Cobitophis, a grouping containing the very elongate species, while Perugia (1892) originally described P. doriae in the genus Eucirrhichthys. The former was synonymised with Acanthophthalmus by Nalbant (1963) and the latter by Roberts (1989).

The family Cobitidae, often referred to as ‘true’ loaches, is widely-distributed across most of Eurasia with the Indian subcontinent, Southeast Asia and China representing particular centres of species diversity.

Phylogenetic analyses by Tang et al. (2006), Šlechtová et al. (2007) and Šlechtová et al. (2008) revealed that the group constitutes a separate genetic lineage to the family Botiidae (the two were previously grouped together under Cobitidae as subfamilies Cobitinae and Botiinae).

In the most recent study Pangio was found to be more closely affiliated with Acantopsis, Acanthopsoides and Kottelatlimia than Lepidocephalichthys as had been previously hypothesised.

All cobitids possess sharp, motile, sub-ocular spines which are normally concealed within a pouch of skin but erected when an individual is stressed, e.g. if removed from the water. Care is therefore necessary as these can become entangled in aquarium nets and with larger species even break human skin.

References

1. Popta, C. M. L., 1903 - Notes from the Leyden Museum 23: 231-233
   Acanthophthalmus shelfordii, n. sp.
2. Bohlen, J., V, Šlechtová, H. H. Tan and R. Britz, 2011 - Molecular Phylogenetics and Evolution 61(3): 854-865
   Phylogeny of the Southeast Asian freshwater fish genus Pangio (Cypriniformes; Cobitidae).
3. Britz, R. and J. Maclaine, 2007 - Ichthyological Exploration of Freshwaters 18(1): 17-30
   A review of the eel-loaches, genus Pangio, from Myanmar (Teleostei: Cypriniformes: Cobitidae).
4. Britz, R. and M. Kottelat, 2010 - Ichthyological Exploration of Freshwaters 20(4): 317-376
   Pangio longimanus, a miniature species of eel-loach from central Laos (Teleostei: Cypriniformes: Cobitidae).
5. Burridge, M. E., 1992 - Copeia 1992(1): 172-186
   Systematics of the Acanthophthalmus kuhlii complex (Teleostei: Cobitidae), with the description of a new species from Sarawak and Brunei.
6. Hadiaty, R. K. and M. Kottelat, 2009 - Zootaxa 2171: 65-68
   Pangio lidi, a new species of loach from eastern Borneo, Indonesia.
7. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
8. 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.
9. Kottelat, M. and K. K. P. Lim, 1993 - Raffles Bulletin of Zoology 41(2): 203-249
   A review of the eel-loaches of the genus Pangio (Teleostei: Cobitidae) from the Malay Peninsula, with descriptions of six new species.
10. Ng, H. H. and H.-H. Tan, 1999 - Zoological Studies 38(3): 350-366
    The fishes of the Endau drainage, Peninsular Malaysia with descriptions of two new species of catfishes (Teleostei: Akysidae, Bagridae).
11. Roberts, T. R., 1989 - Memoirs of the California Academy of Sciences 14: i-xii + 1-210
    The freshwater fishes of Western Borneo (Kalimantan Barat, Indonesia).
12. 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.
13. 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).
14. Šlechtová, V., J. Bohlen and A. Perdices, 2008 - Molecular Phylogenetics and Evolution 47(2): 812-831
    Molecular phylogeny of the freshwater fish family Cobitidae (Cypriniformes: Teleostei): delimitation of genera, mitochondrial introgression and evolution of sexual dimorphism.
15. Šlechtová, V., J. Bohlen 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.