Loaches · Stone & brook loaches

Schistura bolavenensis

Kottelat, 2000

IUCNENDANGERED
CARESNOT LISTED
Scientific size3.5 in8.8 cm standard length
Temperature72–79 °F22–26 °C
pH6.5–7.5neutral
Depthnot recorded
DietBenthic micro-predator of small aquatic insects and other invertebrates in fast, clear water
BreedingEgg-scatterer over gravel/among stones in fast water; no parental care; rarely or never documented in captivity
Sexual dimorphismMinimalNo sexual dimorphism has been documented for this species; data are sparse
PhotographsSee photosGoogle Images →

Schistura bolavenensis is a small stone loach known only from the Bolaven Plateau of southern Laos, where it lives in clear, fast-flowing tributaries of the Xe Kong and Xe Don rivers within the Mekong basin. Reaching under 3.5 in, it is a typical Nemacheilidae micro-predator, picking insects and other small invertebrates off the stony beds of cool upland streams between roughly 800 and 1,656 ft elevation. It has never entered the aquarium trade in any meaningful way and almost nothing is documented about its reproduction; what is well documented is a genuine conservation concern, as its narrow highland range overlaps proposed hydropower dams and bauxite mining that threaten to alter or destroy the very streams it depends on.

What's in the name

Schistura bolavenensisSKIS-tyoo-rah boh-lah-ven-EN-sis

Schistura
  • schistosGreeksplit, divided
  • ouraGreektail — together 'split tail', referring to the typically forked or notched caudal fin of the genus
bolavenensis
  • Bolavenplace namethe Bolaven Plateau of southern Laos
  • -ensisLatinsuffix denoting place of origin — together 'from the Bolaven Plateau'

Taxonomy & naming

Schistura bolavenensis was described by the Swiss ichthyologist Maurice Kottelat in 2000, part of his extensive work resolving the stone-loach faunas of Indochina. The species epithet refers directly to its type locality, the Bolaven Plateau of Champasak and Sekong provinces in southern Laos.

It belongs to the family Nemacheilidae, the stone or brook loaches — by far the largest loach family, with more than 45 genera and over 570 species spread across Asia, Europe and northeastern Africa. Many of these species were historically lumped into the old catch-all genera Nemacheilus or Noemacheilus; modern taxonomy, following the Catalog of Fishes, splits that assemblage into narrower genera such as Schistura, Triplophysa and Barbatula on the basis of fin, scale and skeletal characters. Schistura bolavenensis has always stood in Schistura and there is no synonymy to untangle here — it is simply a poorly known, range-restricted member of one of the hobby's most taxonomically active genera.

Morphology

Like other members of its genus, Schistura bolavenensis is a slender, elongate stone loach built for holding position on the bottom of fast water rather than for open swimming. It is a modestly sized species, with FishBase reporting a maximum standard length of about 3.5 in — smaller than showier botiid loaches and typical for a Schistura confined to a single upland drainage.

As in other Nemacheilidae, the skin carries only small, deeply embedded scales or none at all over parts of the body, leaving it effectively naked and, as with other near-scaleless loaches, sensitive to harsh water conditions and medications. Where present in the genus, an erectile suborbital spine sits in a groove beneath the eye — a defensive feature shared across the stone- and spined-loach lineages. Detailed colour pattern and fin-ray counts for this species are not covered in the available sources, and given how narrowly it has been studied, that gap is honest rather than an oversight.

Habitat

This species is a true stream endemic. It is known only from tributaries of the Xe Kong and Xe Don rivers, part of the Mekong basin, on the Bolaven Plateau of southern Laos — a basalt highland at roughly 800 to 1,656 ft elevation. The streams there run clear, cool and fast over rocky substrates, the classic habitat of Nemacheilidae micro-predators, which cling to and forage among stones in well-oxygenated, current-swept water rather than the slow, warm, vegetated waters favoured by many lowland fish.

This single-plateau distribution is both the species' defining feature and its greatest vulnerability: there is no lowland or floodplain population to fall back on, and any change to the flow, temperature or clarity of its home streams affects the entire known range.

Feeding

Schistura bolavenensis is a benthic micro-predator, foraging over stony stream beds for aquatic insect larvae and other small invertebrates — the diet typical of Schistura and its relatives in fast, clear water. The cached sources describe the closely related genus more broadly as taking small insects, worms, crustaceans and zooplankton, and there is no reason to expect this species departs from that pattern.

In a hypothetical aquarium setting this feeding style would translate to a fish that hunts live and frozen foods such as bloodworm, Artemia and Daphnia enthusiastically but may largely ignore dry flake, since its natural prey is small, moving and bottom-dwelling rather than surface-floating.

Mating

No courtship or spawning behaviour has been documented for Schistura bolavenensis in the sources available, and external sexual dimorphism is not described. This is consistent with the wider genus: most Schistura are restricted stream endemics that have been collected and described from a handful of specimens, with reproductive biology observed in the wild rarely if ever. Data here are genuinely sparse rather than simply unresearched for this account, and any detailed claim about pairing or sexing would be guesswork.

Breeding

As with the great majority of stone and brook loaches, Schistura bolavenensis is not known to have been bred in captivity. The genus as a whole is presumed to be an egg-scatterer, releasing eggs over gravel and among stones in flowing water with no parental care afterward, matching the general reproductive mode of Nemacheilidae. This species has essentially no presence in the aquarium trade, so there is no hobbyist track record to draw on, and the honest summary is that its breeding remains undocumented rather than that it follows any specific ritual.

In the aquarium

Schistura bolavenensis is not an aquarium fish in any practical sense — it has no established presence in the trade, and this account is built from museum and conservation literature rather than hobbyist experience. Were it ever encountered, its needs would follow the general Schistura template: cool, clear, fast-flowing, well-oxygenated water over coarse sand, gravel and rock, with strong water movement (several times tank volume per hour) and frequent partial water changes to replicate the highland stream conditions it evolved in. As a near-scaleless loach it would be expected to be sensitive to copper-based medications and full-strength treatments, warranting the same caution given to other scaleless loaches.

Given its extremely restricted natural range and threatened status, this is not a species to seek out from wild-collected stock even if it were offered — there is no farmed supply, and any specimens in trade would necessarily be taken from an already vulnerable wild population.

Conservation

Schistura bolavenensis is assessed as Endangered on the IUCN Red List. Its entire known distribution is confined to tributary streams of the Xe Kong and Xe Don rivers on the Bolaven Plateau in southern Laos, a small highland area that places the whole species at risk from any single large-scale disturbance.

The principal threats are development pressures specific to that plateau: proposed hydropower dam projects that would alter stream flow and connectivity, and bauxite mining, which threatens to degrade water quality and stream-bed habitat through sedimentation and runoff. As a narrow-range stream endemic with no meaningful presence in the aquarium trade, its future depends entirely on how the Bolaven Plateau's water and mineral resources are managed, not on collecting pressure.

Sources

  1. GBIF — Schistura bolavenensis Kottelat, 2000, species treatments
  2. IUCN Red List — Schistura bolavenensis, Endangered
  3. Seriously Fish — Schistura genus care and habitat notes

Last reviewed 2026-07-01.

How to cite

Aquarist Atlas (2026). Schistura bolavenensis. Aquarist Atlas.https://www.aquaristatlas.com/loaches/schistura-bolavenensis/

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