Taxonomy & naming
Schistura dayi was described by Sunder Lal Hora in 1935, hence the parentheses around his name signalling a later shift of genus from his original placement. It sits in Schistura, by far the largest genus in the stone-loach family Nemacheilidae, which itself is the largest of all the loach families. Older literature and many regional survey papers may still refer to species in this group under the historic catch-all names Nemacheilus or Noemacheilus; the Catalog of Fishes is the authority for the currently valid combination, and it places this species in Schistura.
The species is one of fourteen valid Schistura recognised from peninsular India, the Western Ghats and Sri Lanka, a region that has proven to hold substantial hidden diversity within the genus as taxonomists have worked through what was once lumped together as a handful of "common" stream loaches. The type locality for Schistura dayi is not confirmed in the sources available for this profile, and no additional common name for it has turned up in the material reviewed — it is known to hobbyists and researchers alike essentially only by its scientific name.
Morphology
As a Nemacheilidae, Schistura dayi shares the family's basic stone-loach build: an elongate, only lightly compressed body, a small ventral-facing mouth surrounded by barbels for probing the substrate, and an erectile spine below the eye that the fish can flick out when threatened or handled. The skin carries only tiny, deeply embedded scales, if any are visible at all, which leaves these fish effectively naked to the touch — a detail that matters far more for medication dosing than for appearance.
Detailed measurements, colour pattern and maximum size specific to Schistura dayi were not found in the sources consulted for this profile. Genus-mates in the Schistura group from India and Sri Lanka are typically small, cryptically banded or blotched stream fish adapted to blend against gravel and cobble, and this species can reasonably be assumed to follow that general pattern, but a confident size figure cannot be given without guessing — the honest position is that size and coloration detail for this species is currently data-sparse.
Habitat
Schistura dayi is endemic to India. It has been recorded in fish-assemblage studies from central India, including work examining the interface between rivers and reservoirs, where it was noted as a minor but present component of the local fish community. Like other members of its genus, it is a fish of running fresh water — fast, cool-to-mild, clear, well-oxygenated streams and rivers rather than still, warm, tannin-stained pools.
Beyond the confirmed occurrence in central Indian river systems, the precise range, elevation and specific stream character (gradient, substrate, seasonal flow pattern) for this species were not detailed in the available sources. Given its placement among the peninsular Indian and Western Ghats Schistura, a rocky or gravel-bottomed flowing stream habitat is the reasonable expectation, but exact water-body identity should not be assumed beyond what has been documented.
Feeding
Nemacheilid stone loaches as a group are bottom-foraging micro-predators, working sand, gravel and stones for small invertebrates — insect larvae, worms and tiny crustaceans — rather than grazing algae or browsing plants. Schistura dayi can be expected to feed in the same way, picking prey items from the streambed in its native flowing water.
No species-specific feeding data was found in the sources consulted, so this description follows the well-established pattern for the genus rather than a direct observation of this fish. In captivity, small stone loaches of this type generally accept sinking live and frozen foods such as bloodworm and small crustaceans readily, while showing little interest in flake left to float.
Mating
No courtship or spawning behaviour specific to Schistura dayi has been documented in the sources available for this profile, and there is no confirmed record of dimorphism between the sexes for this species. Stone and brook loaches in general show little obvious external difference between males and females outside brief spawning condition, and without species-specific data this fish should be assumed to follow that pattern rather than have any distinguishing marker asserted for it.
Breeding
Nemacheilidae as a family are egg-scatterers: ripe adults release eggs over gravel and among stones in fast-flowing water, with no nest-building, no cave-guarding and no parental care of eggs or fry afterward — a very different pattern from the cave-spawning or mouthbrooding strategies seen in other fish groups. Schistura dayi has not been reported bred in the aquarium in the sources reviewed here, which is unsurprising: most members of this genus are rarely if ever spawned in captivity, and detailed breeding records for the wild population are similarly sparse.
The honest summary for this species is that it is essentially unbred and undocumented in a breeding context — any keeper attempting to spawn it would be working from genus-level generalities rather than any established protocol specific to Schistura dayi.
In the aquarium
Schistura dayi is not an established aquarium staple, and specific stocking, tank-size or water-parameter guidance for it was not found in the sources consulted. What can be said with confidence follows from its family membership: like other Nemacheilidae, it will do best in cool-to-moderate, clean, fast-flowing, well-oxygenated water over a sand or fine-gravel substrate, and it is likely to appreciate current from a powerhead or filter outflow rather than still water.
Being near-scaleless, stone loaches in this genus are typically sensitive to copper-based treatments and full-strength doses of many standard medications, so a cautious, half-dose approach and close observation for early signs of ich are prudent with any Schistura. Given the general absence of trade or captive-breeding data for this particular species, anyone keeping it should treat it as a genuinely uncommon, poorly documented fish and prioritise stable water quality and enrichment (cover, current, a natural substrate) over any specific numeric target, since none is available from the record.
Conservation
Schistura dayi is assessed as Least Concern on the IUCN Red List, consistent with a widespread distribution within India rather than a narrow single-stream endemic status. The assessment year was not confirmed in the sources reviewed for this profile.
As an Indian freshwater endemic recorded from river systems that also interface with reservoirs, the species sits within a landscape shaped by damming, water abstraction and land-use change typical of much of peninsular India's river network, though no specific population trend or threat data for this species was found. There is no evidence in the sources consulted of a significant aquarium trade in Schistura dayi; it does not appear to be a species reliant on wild collection for the hobby, most likely because it is not meaningfully present in the trade at all.