Black Kuhli Loach
Cobitis oblonga Valenciennes, 1846; Acanthophthalmus javanicus Bleeker, 1860; Acantophthalmus javanicus van Hasselt, 1823 (nomen nudum)
Described from close to the city of Bogor, Jawa Barat (West Java) province on the island of Java, Indonesia, but currently considered widespread with recorded occurrences in Java, Sumatra, Borneo, Peninsular Malaysia and Thailand.
Some populations exhibit lighter or pinkish body colouration and the species will probably turn out to represent a complex of closely-related taxa with at least 4 genetic lineages already identified (Bohlen et al. 2011, also see ‘Notes’ below).
Most commonly found in shallow, slow-moving sections of forest streams or other calm habitats such as swamps, oxbows, and backwaters.
Such habitats are typically shaded from the sun by marginal vegetation and the tree canopy above. The water has a negligible dissolved mineral content, is poorly-buffered and pH can be as low as 3.0 or 4.0 due to release of tannins and organic acids from decaying organic material.
Maximum Standard Length
70 – 80 mm.
Aquarium SizeTop ↑
An aquarium with base measurements of at least 60 ∗ 30 cm or equivalent is recommended.
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 with aquatic plants from genera such as Microsorum, Taxiphyllum, and Cryptocoryne suitable.
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.
Temperature: 21 – 26 °C
pH: 3.5 – 7.0
Hardness: 0 – 143 ppm
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.
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.
There exists at least one documented account of this species being bred in aquaria, though not under controlled conditions.
Among the more readly-available Pangio spp. in the hobby and also traded as ‘Java loach’, ‘cinnamon loach’ and ‘chocolate kuhli loach’.
It’s included in the P. kuhlii-oblonga group of closely-related species within the genus and can be distinguished from other members by its plain to reddish-brown body colouration, lack of nasal barbels, possession of 45-47 vertebrae and relatively deep body (body depth fitting 7.2-7.7 times into SL). P. pangia is very similar in appearance but is a comparatively longer, slimmer fish (body depth fitting 7.6-9.0 times into SL).
Kottelat and Lim (1993) suggested that the P. kuhlii and P. oblonga groups represent two of four such assemblages within the genus alongside the P. anguillaris and P. shelfordii groups.
Members were separated from those of the P. kuhlii, P. shelfordii and P. anguillaris groups by their plain body patterning, 8-9 pectoral-fin rays, 45-51 vertebrae and development of adipose keels on both ventral and dorsal extremes of the caudal peduncle.
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.
Within this third lineage are three sublineages formed by P. filinaris, an apparently undescribed fish from the Temburong River in Brunei referred to as P. cf. oblonga IV, and all other species in the group, respectively.
Species in the P. khulii and P. oblonga groups had previously been separated largely on the basis of colour pattern, i.e., barred vs. plain brown, but in the molecular analysis the barred species grouped within the brown. They also display a high degree of morphological affinity with simlarities in body shape and the number of vertebrae.
One brown specimen even grouped together with the barred P. malayana collected from the same locality rather than any of the other plain fish, suggesting a degree of phenotypic variability within species may also be involved.
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.
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Histoire naturelle des poissons. Tome dix-huitième. Suite du livre dix-huitième. Cyprinoïdes.
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Molecular phylogeny of the freshwater fish family Cobitidae (Cypriniformes: Teleostei): delimitation of genera, mitochondrial introgression and evolution of sexual dimorphism.
- Šlechtová, V., J. Bohlen and H. H. Tan, 2007 - Molecular Phylogenetics and Evolution 44(3): 1358-1365
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