Taxonomy & naming
Neonoemacheilus mengdingensis was described by Zhu and Guo in 1989, with a type locality near Mengding in Gengma County, Yunnan Province, China — the specific epithet mengdingensis simply means "of Mengding," naming the town nearest to where the type specimens were collected. It sits in the genus Neonoemacheilus, one of the many stone-loach genera carved out of the old, over-broad "Noemacheilus" wastebasket as ichthyologists worked through the Nemacheilidae in the late twentieth and early twenty-first centuries.
The family Nemacheilidae is itself the largest loach family by species count, comprising several hundred small, superficially similar stream loaches across Eurasia; genera such as Schistura, Triplophysa, Barbatula and Neonoemacheilus have all absorbed species that were once dumped together under Noemacheilus or Nemacheilus before molecular and morphological work sorted them out. The Catalog of Fishes is the standing authority for the valid combination, and GBIF's taxonomic backbone confirms Neonoemacheilus mengdingensis Zhu & Guo, 1989 as a currently accepted name. No later synonymy or genus reassignment is recorded in the sources consulted for this profile.
Morphology
As a nemacheilid, Neonoemacheilus mengdingensis shares the family's basic stone-loach build: an elongate, sub-cylindrical body, a flattened belly suited to gripping the bottom in fast water, and a small mouth set low on the head for grubbing among stones and gravel. FishBase records it as a demersal, bottom-dwelling fish of subtropical fresh water, with a trophic level of about 2.8, indicating a diet weighted toward small invertebrates with an omnivorous component — consistent with the family's typical feeding ecology.
Detailed measurements, colour pattern, fin-ray counts and other diagnostic morphology are not covered in the sources available for this article, and no maximum length figure could be confirmed; species in this genus and family are generally quite small. Given how little has been published on this species since its original description, it is more honest to flag this as a genuine data gap than to guess at numbers. Many nemacheilids also carry a small erectile suborbital spine typical of the wider Cobitoidea, but its presence in this particular species is not confirmed in the sources here.
Habitat
The species is known from the Salween River basin in Yunnan Province, southwestern China, with its type locality a stream near Mengding, Gengma County — a subtropical part of the upper Salween drainage near the border with Myanmar. FishBase classifies its environment as subtropical, freshwater and demersal, matching the general nemacheilid pattern of clear, fast-flowing, well-oxygenated stream habitat rather than still or lowland water.
As with most small-range stone loaches, published habitat detail beyond the type locality is limited; there is no indication in the available sources of a wider distribution outside this part of the Salween basin, and it should be treated as a narrow-range Yunnan endemic until further survey work says otherwise.
Feeding
FishBase's trophic-level estimate of 2.8 places Neonoemacheilus mengdingensis as a low-level omnivore leaning toward animal matter — the pattern typical of small benthic stone loaches, which pick small invertebrates, insect larvae and other invertebrate prey from among stones and gravel on the streambed, supplementing this with algae and organic detritus. No species-specific feeding study is available in the sources consulted here, so this description follows the general family pattern rather than direct observation of this fish.
There is no record of this species being kept or fed in the aquarium hobby, so no husbandry-based feeding notes exist to draw on.
Mating
No information on courtship, spawning triggers, sexual dimorphism or reproductive behaviour specific to Neonoemacheilus mengdingensis is available in the sources consulted for this profile. This is common for small, narrow-range nemacheilids that are known essentially from their original taxonomic description and subsequent database listings rather than from dedicated field or aquarium studies.
Breeding
Stone and brook loaches of the family Nemacheilidae are, as a rule, egg-scatterers: ripe fish release adhesive or semi-adhesive eggs over gravel and among stones in fast-flowing water, with no parental care of eggs or fry. There is no evidence that Neonoemacheilus mengdingensis has ever been bred in captivity, and it is not part of the aquarium trade, so this profile follows the honest general pattern for the family rather than any species-specific record.
In the aquarium
Neonoemacheilus mengdingensis is not known to be present in the aquarium hobby. There are no husbandry records, water-parameter recommendations, or keeper reports to draw on for this species, and this profile will not invent them. As a general point for the family it belongs to, most Nemacheilidae are cool-to-cool-temperate, fast-flowing-stream specialists that do poorly in warm, still water and, like other scaleless or near-scaleless loaches, tend to be sensitive to copper-based and full-strength medications — but none of that has been verified for this particular species, and it should not be assumed to be available or suitable for aquarium keeping.
Conservation
Neonoemacheilus mengdingensis has not been evaluated by the IUCN Red List, so it carries no formal conservation category here — it is recorded as Not Evaluated rather than assigned a guessed status. As a fish known only from a limited part of the Salween basin in Yunnan, it shares the general vulnerability of narrow-range stream endemics to habitat degradation, damming and water-quality pressure in the region, but no species-specific assessment or population data exists in the sources available to support a more specific statement.