Taxonomy & naming
Nemacheilus tebo was described by Renny Kurnia Hadiaty and Maurice Kottelat in 2009, in the Raffles Bulletin of Zoology (57: 119–125), as a new loach from the Sangkulirang karst of East Kalimantan, Indonesian Borneo. It was described directly in the genus Nemacheilus rather than transferred from an older combination, and the Catalog of Fishes — the authority for valid names — lists it as a valid species in that genus.
It belongs to the family Nemacheilidae, the stone or brook loaches, the largest family of true loaches and one whose genus-level classification (Nemacheilus, Schistura, Barbatula, Triplophysa and others) has been repeatedly reshuffled as karst and highland drainages across Asia are surveyed. The holotype (MZB 13367, 2 in SL) and a paratype (CMK 18909, 2 in SL, male) anchor the description; the species name references Lake Tebo, part of the type locality.
Morphology
Nemacheilus tebo is a small loach, with the type series measuring roughly 2 in SL, males included. Like other members of the genus it has an elongate, subcylindrical body and a row of dark bars along the flank — in this species 11 to 16 of them, with the bars anterior to the dorsal fin noticeably shorter and often fused into a single large blotch, while the bars behind the dorsal fin remain distinct and separate.
As in other Nemacheilidae, the skin is effectively naked — covered only in very small, deeply embedded scales — and the species should be assumed to carry the erectile suborbital spine typical of the wider Cobitoidea group, a feature used cautiously in defence and in handling. Fine anatomical distinctions of this kind are exactly what separate N. tebo from its close relatives in the same karst system, and the original description should be consulted for full diagnostic detail.
Habitat
This species is a narrow-range endemic of the Sangkulirang peninsula karst in East Kalimantan, Indonesia, known from the Lake Tebo drainage on Borneo. Karst streams of this kind are typically clear, cool-to-moderate in temperature, well-oxygenated, and run over limestone-influenced substrate with stable year-round flow fed by underground drainage — very different from the warm, still, tannin-stained waters associated with many Southeast Asian blackwater fishes.
FishBase classifies it as a benthopelagic tropical freshwater species. No detailed limnological data (temperature range, pH, exact flow regime) have been published for the Lake Tebo drainage specifically, so keepers and researchers alike should treat the finer habitat parameters as data-sparse rather than assume they mirror a lowland river.
Feeding
No feeding study has been published for Nemacheilus tebo specifically. Based on its family and genus, it should be treated as a benthic micro-predator, working the stream bottom for small aquatic invertebrates — insect larvae, small crustaceans and similar prey — in the manner typical of Nemacheilus and other stone loaches from fast, clear water.
In a captive setting this points toward small live and frozen foods (bloodworm, daphnia, chopped invertebrates) and sinking preparations rather than flake, which a benthic micro-predator of this kind is unlikely to notice or compete for at the surface.
Mating
Nothing has been published on courtship, spawning behaviour, or sexual dimorphism in Nemacheilus tebo beyond the sex of the type specimens (the paratype is recorded as male). No external dimorphism has been described, and none should be assumed.
Breeding
No captive or wild breeding observations have been recorded for this species. Stone and brook loaches (Nemacheilidae) as a group are egg-scatterers, releasing eggs over gravel and among stones in fast-flowing water with no parental care, and they are rarely bred in the aquarium; N. tebo, a narrow-range karst endemic with essentially no trade presence, fits that pattern and should be assumed unbred in captivity rather than described with invented spawning detail.
In the aquarium
Nemacheilus tebo is not an established aquarium fish — it has no meaningful presence in the trade, and this profile is written from the type description and general Nemacheilidae biology rather than from keeper experience. Should it ever appear, it should be treated like other stone/brook loaches: cool-to-moderate, clear, fast-flowing, well-oxygenated water over a fine gravel or sand substrate, since karst-stream fish of this kind are poorly suited to warm, still, low-oxygen conditions.
As with other near-scaleless loaches, caution with copper-based and full-strength medications is warranted, and — as a small benthic species — it would need calm tankmates that will not out-compete it at the bottom. Given how little is documented, anyone attempting to keep this species should prioritise close observation and record-keeping over assumptions borrowed from better-known Nemacheilus.
Conservation
The IUCN Red List assesses Nemacheilus tebo as Vulnerable (2019), reflecting its known occurrence in a single, narrow karst drainage — the kind of restricted range that makes stream endemics of this family especially exposed to local habitat disturbance. The Sangkulirang karst is a distinctive and biologically significant limestone landscape in East Kalimantan, and pressures on karst systems generally include quarrying, deforestation of the surrounding catchment, and changes to groundwater-fed stream flow.
No evidence points to aquarium collection as a factor for this species; its conservation concern is driven by its inherently narrow distribution rather than trade demand. As with many recently described karst endemics, further survey work would help clarify its true range and the specific pressures it faces.