Taxonomy & naming
Pangio lidi was described by Renny Kurnia Hadiaty and Maurice Kottelat in 2009, based on specimens collected from Sungai Petung Kanan in the Mahakam River drainage of East Kalimantan, Indonesian Borneo. The species epithet lidi has not been publicly glossed in accessible literature, but the name follows the authors' descriptive practice for new Pangio from Sundaland. The Catalog of Fishes (Eschmeyer, CAS) treats it as a valid species in the genus Pangio.
Pangio belongs to the family Cobitidae, the true loaches. The genus was formerly known in the hobby almost exclusively as Acanthophthalmus — a name meaning 'thorn-eye', after the erectile suborbital spine — but Acanthophthalmus is now treated as a junior synonym of Pangio, which has priority. The common name 'kuhli loach' properly belongs to Pangio kuhlii, but in trade and hobbyist use it has spread to cover the whole Pangio genus. Pangio lidi has no established common name in the English-language trade; it is essentially unknown in the hobby.
Morphology
Pangio lidi reaches a maximum recorded standard length of 2.5 in, placing it among the smaller members of the genus. Like all Pangio it is distinctively eel-shaped: the body is long, cylindrical and tapers toward a small head and a rounded tail, giving it a snake-like profile suited to pushing through leaf litter and between sand grains. Precise colour pattern data for P. lidi are sparse in published sources, but the genus typically shows some combination of pale or yellowish ground colour with dark banding, barring or spotting.
The skin is near-scaleless — deeply embedded, vestigial scales leave the surface effectively smooth to the touch, a feature that has direct implications for medication sensitivity. Beneath each eye lies an erectile bifid suborbital spine, the hallmark of cobitid loaches; when threatened or handled, the fish can flick these spines outward, which makes it easy for them to tangle in nets. Pangio lidi is reported to be a facultative air-breather, supplementing gill respiration with intestinal uptake of atmospheric oxygen in poorly oxygenated water — a trait widespread across the family.
Habitat
Pangio lidi is known only from the Mahakam River drainage in East Kalimantan, Borneo, Indonesia. The type locality, Sungai Petung Kanan, is a small tributary characteristic of Bornean lowland rivers: slow to gently flowing water beneath large riparian trees, with a substrate of fine sand and accumulated leaf litter, and water shaded and often tannin-stained by the canopy above. The species is described as demersal — a bottom-dweller — consistent with the burrowing, substrate-sifting lifestyle of the kuhli loach group.
Water conditions in these Bornean lowland streams are typically warm (around 73–81 °F), soft, and slightly to moderately acidic, with low conductivity and gentle currents. The heavy shading from intact riparian forest keeps light levels low and temperatures stable. Pangio lidi is a forest-stream specialist; it is neither a cool fast-water hillstream fish nor a tolerant generalist, and its likely range is small.
Feeding
Like other Pangio, P. lidi is a micro-omnivore and substrate sifter. In its native streams it forages nocturnally over fine sediment for small invertebrates — worms, insect larvae, tiny crustaceans — as well as organic detritus caught in leaf litter. It is not a surface feeder; it hunts at and just below the substrate surface, working the sand through the night.
In the aquarium, kuhli loaches in general accept sinking pellets, gel food, and frozen or live small invertebrates such as bloodworm and blackworm. A key husbandry point is that these fish feed almost exclusively after dark and are easily outcompeted at the surface; food offered at lights-out and sized to reach the bottom promptly ensures they are not chronically underfed. P. lidi is not available in the trade, but the genus-level feeding biology is well established and consistent across species.
Mating
No observations of mating behaviour have been published for Pangio lidi. Data on reproductive biology are absent from the sources available, and the species is not known in captivity. Based on the broader biology of the genus, sexing Pangio is generally difficult: females are typically deeper-bodied when gravid, but outside of breeding condition the two sexes are very similar externally, and reliable dimorphism characters have not been described for most species.
In better-studied Pangio such as P. kuhlii, spawning appears loosely associated with seasonal rainfall and changes in water conditions. This is consistent with the monsoon-driven seasonal cycles that structure reproduction in many Southeast Asian freshwater fishes, but detailed field observations for P. lidi do not exist in the accessible literature.
Breeding
Pangio lidi has not been bred in the aquarium, and given how rarely it appears in the trade, this is unlikely to change in the near term. Kuhli loaches as a group are rarely spawned by hobbyists; when spawning does occur in a mature, well-planted tank, the fish scatter small, greenish, adhesive eggs among floating plant roots or at the water surface, with no parental care whatsoever — adults will consume eggs and fry if given the chance. The eggs are reported to hatch within approximately 24 hours, and fry require infusoria or very fine live food initially.
The aquarium trade in Pangio loaches is supplied almost entirely by wild-collected fish, not captive breeding. The conditions that would trigger spawning — seasonal changes in water volume, temperature, chemistry and daylength tied to the monsoon cycle — are difficult to replicate in a home tank. The honest picture for P. lidi, and for most of its genus, is that breeding is very rarely achieved and should not be expected.
In the aquarium
Pangio lidi is not available in the aquarium trade and is essentially unknown outside scientific collections. For anyone who encounters it or wishes to apply kuhli-loach husbandry to a closely related Pangio: the genus needs a deep layer of fine, smooth sand — sharp gravel or bare-bottomed tanks damage the delicate scaleless skin and discourage the burrowing behaviour that is fundamental to the fish's well-being. Dense planting, leaf litter, and plenty of caves, roots or cork bark give kuhli loaches the cover they require to feel secure; a shy or stressed group will simply hide and waste away.
Pangio loaches should be kept in groups of at least three to six individuals; solitary specimens are notably more timid and stressed. Being near-scaleless, they absorb medications through the skin at a higher rate than scaled fish and are sensitive to copper and to full-strength doses of many common treatments — when disease strikes the tank, half-doses of copper-free medications are the standard precaution. At the same time, loaches are often among the first fish to show signs of ich, so close observation matters. Water should be warm (around 73–81 °F), soft, slightly acidic, and well-filtered but with gentle flow; bright overhead lighting and sparse cover are the single easiest way to stress these fish into hiding permanently.
Conservation
Pangio lidi is assessed as Data Deficient on the IUCN Red List (2019). The designation reflects genuine uncertainty: the species is known from a very limited number of specimens collected from a single drainage, its precise range, population size and trend are unknown, and field surveys targeting it have not been published. Data Deficient does not mean unthreatened — it means the information needed to make an honest assessment does not yet exist.
The Mahakam River drainage, like much of East Kalimantan, sits inside one of the most intensively developed regions of Borneo. Oil palm monoculture is the primary identified threat: plantation establishment strips riparian cover, increases sedimentation and nutrient loading, and delivers pesticide and herbicide runoff directly into small streams. These pressures are exactly the kind that eliminate small, range-restricted stream specialists. The trade in P. lidi is negligible — the species is not commercially collected — so the aquarium hobby is not a concern here. The conservation need is better field data to establish whether P. lidi is more widespread than currently known, and ongoing protection of intact lowland forest within its catchment.