Taxonomy & naming
Claea tongziensis was described by Zhao, Lv, Huang & Liu in 2026 in the journal ZooKeys, based on specimens collected from the headwaters of the Tongzi River in Tongzi County, Guizhou Province, China — the locality that gives the species its epithet. It sits in the genus Claea, a small group of Chinese stone loaches centred on the upper and middle Yangtze basin within Nemacheilidae, the stone and brook loaches, by far the largest family in the loach superfamily Cobitoidea.
The genus Claea has grown steadily as researchers work through China's karst-riddled Guizhou drainages: alongside the long-recognized C. dabryi, C. minibarba and C. wulongensis, several cave- and stream-dwelling species have been added from the Chishui and Wujiang systems in recent years, of which C. tongziensis is one. The Catalog of Fishes is the standing authority for the valid combination. In molecular analyses based on mitochondrial cytb and cox1 sequences, C. tongziensis formed its own monophyletic lineage, well separated from its congeners (2.82–6.41% genetic distance on cytb), supporting its status as a distinct species alongside the morphological evidence.
Morphology
The original description diagnoses Claea tongziensis by a combination of characters rather than any single striking feature: seven branched dorsal-fin rays, three unbranched anal-fin rays, 4+40–42 vertebrae, a prominent processus dentiformis (a tooth-like process on the lower jaw, a diagnostic feature shared across the genus), a prepelvic length of 46.9–51.7% of standard length, pelvic–anal distance 23.8–28.6% SL, anus–anal distance 4.7–7.0% SL, eye diameter 13.5–18.5% of head length, interorbital width 22.2–29.6% HL, and an outer rostral barbel reaching 18.9–29.3% HL. No maximum length in millimetres is given in the abstract-level source reviewed here, so exact adult size remains unconfirmed.
As a nemacheilid it has the family's typical build: a slender, elongate, near-scaleless body suited to holding position on stony stream beds, with barbels around the mouth for probing gravel and rock crevices for food. The type series is preserved in 10% formalin and figured from multiple angles (lateral, dorsal, ventral, and head views) in the original paper, which focuses on meristic and morphometric ratios rather than colour pattern description.
Habitat
Claea tongziensis is known from the headwaters of the Tongzi River, a tributary of the Chishui River within the middle Yangtze basin, near Shiban Village in the Mazong Miao Ethnic Township of Tongzi County, Guizhou Province, China (28.2235°N, 106.9331°E), at an elevation of about 1,180 ft. This is a surface headwater stream rather than a cave or underground system — unlike some of its Claea relatives, which include documented cave-dwelling species from the same general karst region of Guizhou.
No water temperature, pH or hardness data are reported in the abstract-level source available here. Given the elevation and the general pattern for upland Yangtze-basin headwater streams, cool, clear, fast-flowing, well-oxygenated water is a reasonable expectation, but this is inference from setting rather than a measured figure for this species.
Feeding
No dietary study has been published for Claea tongziensis specifically. The prominent processus dentiformis noted in the diagnosis — a dentiform process on the lower jaw — is a feature shared across Claea and typical of nemacheilids that graze biofilm and algae from rock surfaces as well as picking small invertebrates from the substrate, so a similar mixed grazing-and-micro-predation diet is plausible for this species, though unconfirmed.
In the absence of direct data, the safest statement is that it likely follows the broad Nemacheilidae pattern: foraging along stream-bed gravel and rock for aquatic insect larvae and other small invertebrates, supplemented by algae and biofilm scraped from stone surfaces.
Mating
No courtship or spawning behaviour has been documented for Claea tongziensis, and the original description does not report sexual dimorphism. Nothing beyond the taxonomic diagnosis and molecular data has been published on its reproductive biology.
As with most narrow-range Nemacheilidae described from a single stream system, reproductive behaviour here should be treated as unknown rather than inferred with any confidence beyond the general family pattern of egg-scattering without pair formation.
Breeding
Breeding has not been documented for this species, in captivity or in the wild. Nemacheilidae as a family are typically egg-scatterers, releasing eggs over gravel and among stones in flowing water with no parental care, and Claea tongziensis is presumed to follow this pattern based on its family placement — but this is inference, not observation.
The species has no history in the aquarium hobby, and given how recently it was described and how narrow its known range is, captive breeding data simply does not exist.
In the aquarium
Claea tongziensis is not an aquarium fish. It was described in 2026 from a single headwater locality in Guizhou Province and has no history of collection for the ornamental trade. Any care guidance would have to be extrapolated cautiously from its genus and family rather than drawn from direct experience with this species.
Were it ever encountered, the general nemacheilid template would apply: cool, clear, fast-flowing, well-oxygenated water over a rock and gravel substrate, and the same caution around copper-based and full-strength medications warranted by the family's typically scant scale cover. This is inference from genus and family, not documented fact for this species.
Conservation
Claea tongziensis has not been evaluated by the IUCN Red List, carrying no formal conservation status as a species described only in 2026 from a single headwater stream. It should be treated as data-deficient in practice even though its formal category is Not Evaluated.
Single-locality headwater endemics in Guizhou's karst terrain are inherently vulnerable to stream-scale disturbances such as damming, water diversion, sedimentation and pollution, but no population assessment or trend data exist for this species specifically. There is no evidence of any aquarium trade in this fish.