Taxonomy & naming
Triplophysa dalaica was described by the Russian naturalist Karl Friedrich Kessler in 1876. It belongs to the genus Triplophysa, part of the family Nemacheilidae — the stone or brook loaches, the largest family within the loach superfamily Cobitoidea and one that has been extensively reshuffled over the past few decades as older catch-all genera such as Nemacheilus and Noemacheilus were split apart. The Catalog of Fishes, the authority for valid names, confirms Triplophysa dalaica (Kessler, 1876) as the currently accepted combination, and it has held its genus placement without the renaming churn seen in many related nemacheilids.
The species epithet dalaica refers to its type locality, Lake Dali Nur (also transliterated Dalai Nor or Hulun Lake), the alkaline plateau lake in Inner Mongolia where it was first collected. Genus-level, Triplophysa is one of the most species-rich loach genera, radiating widely across the high-altitude drainages of the Tibetan Plateau and Central Asia; T. dalaica sits at the eastern, lower-altitude edge of that radiation. The name Nemacheilus djaggasteensis is treated as a synonym of this species in Eschmeyer's Catalog of Fishes.
Morphology
Triplophysa dalaica is a small, elongate stone loach reaching a maximum recorded length of about 2.5 in standard length — modest even by nemacheilid standards. Like other members of the family it has a cylindrical, only mildly compressed body, a blunt head with barbels around the mouth for probing the substrate, and the near-scaleless or very finely scaled skin typical of true loaches, which leaves the fish sensitive to harsh water treatments. Nemacheilids as a group lack the erectile suborbital spine that defines the botiid loaches (clown, yoyo, skunk and their relatives); Triplophysa instead relies on its small size, cryptic coloration and benthic habits to avoid predation.
Detailed morphological description specific to this species beyond the FishBase measurements is sparse in the available literature, consistent with a fish known mainly from ecological and genomic studies of its home lake rather than from taxonomic or hobbyist accounts.
Habitat
This species is essentially restricted to northern China: it is recorded from Lake Dali Nur (Hulun Lake) in Inner Mongolia, at an altitude of roughly 1,741 ft, and from artesian and spring waters and tributaries feeding into the wider Yellow River system on the plateau. Lake Dali Nur is remarkable among fish habitats for its water chemistry — it is a closed, terminal alkaline-saline lake with pH measured between about 8.25 and 9.6, alkalinity above 50 mg/L and salinity around 6 parts per thousand, roughly a fifth the salinity of seawater. Triplophysa dalaica is one of only three fish species known to live and reproduce successfully in this environment, alongside a handful of other alkaline-tolerant plateau specialists.
As a member of a genus centred on the cold, low-oxygen, high-altitude waters of the Tibetan Plateau and its margins, T. dalaica is adapted to cool-to-cold conditions rather than tropical warmth; the genus as a whole shows tolerance for low temperature, low dissolved oxygen and elevated salinity/alkalinity, and this species is the clearest example of that tolerance being pushed to an extreme. It occupies both the open lake as a benthopelagic fish and the surrounding spring-fed and artesian waters of the plateau.
Feeding
Specific dietary data for Triplophysa dalaica has not been located in the available sources, but as a benthic member of the genus Triplophysa it almost certainly forages along the lake and stream bottom for small invertebrates and insect larvae, in keeping with the feeding ecology described broadly for benthic cypriniform loaches. No aquarium feeding records exist for the species, since it is not established in the hobby; the honest position is that its diet is inferred from its genus and habits rather than documented in detail.
Mating
No species-specific courtship or spawning behaviour has been documented for Triplophysa dalaica in the available literature. Studies of the genus note that Triplophysa species show periodic migration and what has been described as selective spawning behaviour associated with their high-altitude habitats, but detailed accounts of this species' reproductive behaviour, timing or triggers are not available. This gap is typical for a fish known mainly through ecological and population-genomic study of an unusual lake system rather than through targeted reproductive biology or aquarium observation.
Breeding
Triplophysa dalaica is not a fish that is bred in home aquaria, and it is not established in the ornamental trade at all. Based on the pattern seen across the stone and brook loaches (Nemacheilidae), the expected mode is an egg-scatterer that releases eggs over gravel or among stones in flowing or lake-margin water, with no parental care afterwards — the same basic strategy used by its relatives in fast Asian and European streams. This is inferred from the genus rather than confirmed for T. dalaica specifically, and no aquarium or hatchery spawning records for the species exist. As with most nemacheilids, the honest summary is that breeding biology is essentially undocumented and the fish is not part of any captive-breeding program.
In the aquarium
Triplophysa dalaica has no meaningful presence in the aquarium hobby; it is a scientifically interesting extremophile rather than an ornamental species, and no husbandry track record exists to draw on. Were it ever kept, the responsible approach — following both its genus and its lake of origin — would be cool water rather than a tropical setup, since it comes from a high-altitude plateau lake and associated spring waters, not a warm lowland stream. Any keeper attempting it would also need to reckon with its adaptation to highly alkaline, mineral-rich water, a chemistry very different from the soft, often acidic water most loaches are kept in, and with the general loach sensitivity to copper and full-strength medications that comes with near-scaleless skin. In practice this is a fish for researchers studying alkaline-lake adaptation, not for aquarists, and no reliable sourcing, tank-size or diet recommendations can honestly be given.
Conservation
Triplophysa dalaica is assessed by the IUCN Red List as Least Concern. It is not a narrow single-stream endemic in the usual sense that makes many nemacheilids Data Deficient — it maintains a stable, thriving population in Lake Dali Nur and occurs more broadly across artesian and spring waters and Yellow River tributaries on the Inner Mongolian plateau, giving it a wider effective range and no evidence of population decline.
Its main point of conservation interest is ecological rather than a trade or habitat-loss story: it is one of a small handful of fish species that has evolved to tolerate the extreme alkalinity and salinity of Lake Dali Nur, making it a subject of genomic and physiological research into environmental adaptation rather than a species under documented threat. There is no evidence in the available sources of aquarium-trade collection pressure on this species, consistent with its near-total absence from the hobby.