Taxonomy & naming
Nemacheilus tuberigum was described by Renny Kurnia Hadiaty and Daniel Siebert in 2001, part of a wave of new stone-loach descriptions from Sumatra and Borneo in the late 1990s and early 2000s as Indonesian streams were surveyed more thoroughly. It sits in the genus Nemacheilus, within the family Nemacheilidae — by far the largest loach family, encompassing hundreds of small, superficially similar "stone" or "brook" loaches distributed across South, Southeast and East Asia. The Catalog of Fishes is the governing authority for the valid combination, and it currently keeps this species in Nemacheilus.
The species epithet, tuberigum, is built from Latin tuber (a swelling or lump) combined with a form of magnus (large), together meaning roughly "large-tubercled" or "having large tubercles" — a direct reference to the prominent tubercles on the caudal peduncle noted in the original description. Nemacheilid taxonomy has been reshuffled repeatedly as older, broad genera such as Nemacheilus and Noemacheilus have been split; species once lumped together are now routinely moved to Schistura, Barbatula, Triplophysa and other segregate genera. No such reassignment for N. tuberigum is reflected in the available sources, so it is treated here under its original genus, Nemacheilus.
Morphology
Nemacheilus tuberigum is a small, elongate loach reaching roughly 2 in in standard length — modest even by the standards of a family built almost entirely of small fish. Counts recorded in the description include 13 dorsal-fin rays and 8 anal-fin rays, with 11 to 15 dorsal saddles and 8 to 13 lateral blotches marking the flank, a typical stone-loach pattern of banding and blotching over a pale-to-olive ground colour that helps it disappear against gravel and cobble.
As in other Nemacheilidae, the body carries an erectile suborbital spine and is effectively naked to the eye, the scales being tiny and deeply embedded rather than forming an obvious armour — both points that matter for handling and medication, discussed further under Aquarium. The feature that gives the species its name is a set of unusually large tubercles on the caudal peduncle, a detail singled out in the original description; tubercles of this kind are common secondary structures in nemacheilids and are often more developed in breeding males, though the available sources do not confirm sex-specific development in this particular species.
Habitat
Nemacheilus tuberigum is endemic to Sumatra, Indonesia, known specifically from stream systems in the province of Aceh at the island's northern end. Like the great majority of its family, it is a fish of clear, fast-flowing, well-oxygenated streams rather than still or sluggish water — the typical nemacheilid habitat is a stony or gravel-bottomed watercourse with good current, cool-to-moderate temperatures for the tropics, and high dissolved oxygen.
Because the species is known from a narrow range on a single island, and because detailed habitat surveys have not been captured in the available sources, further specifics on substrate, riparian cover or exact stream order cannot be stated with confidence here — this is one of the many nemacheilids best described honestly as data-sparse rather than embellished with unverified detail.
Feeding
No diet-specific study of Nemacheilus tuberigum has been captured in the available sources. Going by the near-universal pattern in Nemacheilidae, it is reasonable to describe it as a bottom-foraging micro-predator, picking small aquatic invertebrates — insect larvae, tiny crustaceans and similar invertebrate prey — from among stream gravel and cobble, in the same way as its well-studied relatives.
In an aquarium setting extrapolated from the family's general habits, such a fish would be expected to take small live and frozen foods (bloodworm, brine shrimp, chopped invertebrates) and sinking prepared foods offered at the substrate, with flake that stays in midwater likely to be ignored. This should be read as an inference from family-level biology rather than a documented fact about this species specifically.
Mating
No description of courtship, spawning behaviour or sexual dimorphism has been captured in the available sources for Nemacheilus tuberigum. Stone and brook loaches in general are egg-scattering fish with no pair bond and no parental care, and reproduction in the wild is generally tied to fast, well-oxygenated flowing water rather than to any nest, cave or brooding structure. Beyond that family-level generalisation, there is nothing specific to report for this species, and it would be irresponsible to invent detail on tubercle-related courtship displays or seasonal timing that the sources do not support.
Breeding
As with the overwhelming majority of Nemacheilidae, Nemacheilus tuberigum is best assumed to be an egg-scatterer that broadcasts eggs over gravel and among stones in fast-flowing water, with no parental care of eggs or fry. There is no record in the available sources of this species being bred in captivity, and given how narrowly it is known — a single-island endemic described only in 2001 — that is unsurprising; most Nemacheilidae are never bred in home aquaria at all, and this data-sparse species offers nothing to contradict that pattern.
Given the near-total absence of published husbandry or breeding accounts, keepers should not expect to reproduce this fish and should treat any wild or farmed stock as effectively non-renewable in the trade — another reason, alongside its narrow endemic range, to treat the species with conservation caution rather than as a routine aquarium subject.
In the aquarium
Nemacheilus tuberigum is essentially unknown in the aquarium hobby, and no dedicated care profile has been captured in the available sources. What can be responsibly said follows from its family and habitat: as a small (around 2 in), fast-water stone loach, it would be expected to need clear, cool-to-moderate, well-oxygenated, well-filtered water with strong current and a gravel or cobble substrate, rather than the warm, still conditions suited to many other aquarium loaches — a still, warm blackwater setup would be the wrong environment for a fish built for riffles and flow.
As in other nemacheilids, the near-scaleless skin and erectile suborbital spine mean careful handling and caution with medications is warranted: this family is generally sensitive to copper and to full-strength doses of many treatments, so a half-dose, closely-monitored approach is the safer default whenever a fish of this type needs treatment. Given how little is documented about this specific species, and its precarious, single-region status, hobbyists are better served appreciating it as a case study in stream endemism than seeking it out as a display fish.
Conservation
Nemacheilus tuberigum is assessed by the IUCN Red List as Vulnerable. As a narrow-range endemic known only from stream systems in Aceh, Sumatra, it fits the classic profile of an at-risk nemacheilid: a single-island, single-drainage-type distribution that leaves it exposed to any localised habitat disturbance — deforestation, water extraction, pollution or stream modification — with no other populations to buffer a decline.
There is no evidence in the available sources of a significant aquarium trade in this species, and its conservation risk should be understood as driven by habitat pressure on Sumatran streams generally rather than by collection for the hobby. As with many such Sundaland endemics, the responsible position for the hobby is to leave collection pressure off an already-vulnerable population and to treat its Red List status as a signal of a fragile, poorly-known freshwater ecosystem rather than as an invitation to seek the fish out.