Taxonomy & naming
Triplophysa markehenensis was described by Zhu and Wu in 1981, part of a wave of Chinese loach descriptions from the 1970s and 1980s that documented the extraordinary diversity of stone loaches across the Qinghai-Tibet Plateau and its river headwaters. It sits in the genus Triplophysa, within the family Nemacheilidae — the true stone or brook loaches, by far the largest loach family and one that has been repeatedly reshuffled as ichthyologists split the old, catch-all genera Nemacheilus and Noemacheilus into Triplophysa, Schistura, Barbatula and others.
The species epithet markehenensis refers to its type locality on the Maerke River (also transliterated Markehe), a headwater tributary of the upper Dadu River in Qinghai Province — a naming pattern typical of these narrowly distributed plateau endemics, each often described from a single stream system. The Catalog of Fishes is the authority for the currently valid combination, and no subsequent revision affecting this species has been noted here; it remains in Triplophysa.
Morphology
This is a small, elongate stone loach, reaching a recorded maximum of about 4.5 in standard length, though most individuals run smaller, around 3 in. Like other Triplophysa it has a shovel-shaped lower jaw suited to scraping and probing rocky and gravel substrates, a dorsal fin with 7–8 branched rays, and an anal fin with 5–6 branched rays.
As with the genus generally, the skin is effectively naked — the scales are tiny and deeply embedded rather than forming an overlapping armor — which leaves stone loaches sensitive to skin damage, parasites and strong medications. Triplophysa and its Nemacheilidae relatives are barbeled, sensory bottom-feeders, using touch and taste to work over stony substrate in current; several genera in the family carry a small erectile suborbital spine, a family-wide trait, though the detailed anatomy of this particular species is not documented in the sources available here.
Habitat
Triplophysa markehenensis is endemic to the upper Yangtze River basin in western China, recorded from the Jinsha, Yalong and Dadu (including the Maerke/Markehe) river systems across Qinghai, Sichuan and Yunnan provinces. Its type locality is the Maerke River, a headwater tributary of the upper Dadu, in Banma County, Qinghai Province.
This is a high-altitude, benthopelagic river fish, living on the bed of fast-flowing, cold, oxygen-rich plateau streams — the classic habitat of Triplophysa across the Qinghai-Tibet Plateau and Himalaya. No specific temperature or chemistry readings for this stream system are available in the sources consulted, but the genus as a whole is built for cool, clear, swiftly moving water over rock and gravel, not for warm or still conditions.
Feeding
No diet study specific to Triplophysa markehenensis was found. Nemacheilid stone loaches in general, and Triplophysa in particular, are benthic micro-predators: they forage over rocky and gravel substrate for small aquatic invertebrates, insect larvae and other invertebrate prey, supplementing this with diatoms and other biofilm grazed from stone surfaces.
In the near-total absence of aquarium records for this species, the safest working assumption — consistent with its close relatives — is a fish that would take small live and frozen foods (bloodworm, brine shrimp, chopped invertebrates) and sinking foods offered at the substrate, and that would likely ignore floating flake.
Mating
There is no documented account of courtship or spawning behavior for this species. Nothing in the sources consulted describes sexual dimorphism, seasonal spawning migrations, or mate selection in Triplophysa markehenensis specifically. Stone and brook loaches in Nemacheilidae generally are egg-scatterers rather than pair-forming or territorial spawners, releasing eggs into fast water over gravel with no courtship display or nest-building recorded for the family.
Breeding
Data are sparse to the point of absence: this species has no known aquarium history and no published breeding account. Based on the well-documented habits of Nemacheilidae as a whole, the expected pattern is an egg-scatterer that releases eggs over gravel and among stones in fast-flowing water, with no parental care of eggs or fry afterward.
Stone and brook loaches of this kind are rarely if ever bred in captivity; almost none has an aquarium-verified spawning record, and Triplophysa markehenensis — never having entered the hobby — is no exception. Any claim beyond "probably an unguarded egg-scatterer, rarely or never bred" would be guesswork, so none is made here.
In the aquarium
Triplophysa markehenensis is not known to be present in the aquarium trade, and no keeper-reported care record for it was found. It should not be assumed to tolerate the warm, still conditions often given to tropical loaches: as a high-altitude Yangtze-headwater endemic, its genus-mates are cold-to-cool-water specialists that need strong current and high dissolved oxygen, and a fish from this lineage would very likely fare poorly in a typical warm community tank.
If ever kept, the general precautions that apply to Nemacheilidae and to loaches generally would be prudent: a fine, soft substrate that will not abrade the barbels, rockwork and gravel to mimic a stony streambed, strong flow and aeration, and caution with medications given the near-scaleless skin typical of the family. None of this is verified for the species itself — it is inference from its relatives, not observation, and should be treated accordingly.
Conservation
Triplophysa markehenensis has not been assessed on the IUCN Red List and is therefore classified here as Not Evaluated (NE) rather than assigned a guessed category. As a narrow-range endemic apparently restricted to a handful of upper Yangtze headwater tributaries on the Qinghai-Tibet Plateau margin, it fits the profile of many Nemacheilidae species: poorly surveyed, likely naturally restricted in range, and with no documented population trend.
The upper Yangtze headwaters face pressures typical of the region — hydropower development, water abstraction and habitat alteration on plateau rivers — but no source consulted here documents specific threats or population data for this species. Given the total absence of an aquarium trade for it, any conservation concern would stem from habitat change in its native range rather than collection pressure.