Taxonomy & naming
Rasbora hobelmani was described by Maurice Kottelat in 1984 from material collected in Chiengmai Province, northern Thailand. The Catalog of Fishes (Eschmeyer, CAS — the authority for valid names) records the valid combination as Rasbora hobelmani Kottelat, 1984, with the type locality in the upland stream system of that province.
The genus Rasbora, in its traditional broad sense, is a large and heterogeneous assemblage of small Asian cyprinids that has been progressively carved up since the late 1990s. Kottelat and Witte (1999) erected Trigonostigma for the harlequin and related leaf-spawning rasboras, while Boraras, Trigonopoma, Brevibora, Kottelatia and Rasboroides were established for other groups formerly lumped into Rasbora. R. hobelmani has not been reassigned and remains in Rasbora sensu stricto in current usage. A phylogenetic study of cyprinid mitogenomes (published in the Journal of Ichthyology, Springer Nature) confirms its placement within the family Cyprinidae but adds little at the species level.
Kottelat is among the most prolific describers of Southeast Asian freshwater fishes; his 1984 survey of Thai cyprinids brought several upland species to science, of which R. hobelmani was one.
Morphology
Rasbora hobelmani is a slim, torpedo-shaped cyprinid with the laterally compressed body typical of the genus. FishBase records a maximum standard length of 2.5 in, placing it in the mid-range for Rasbora. The mouth is small and terminal to slightly upturned, consistent with a midwater to surface feeding habit.
Detailed published descriptions of the species' colour pattern and scale counts are not widely reproduced in accessible secondary sources, and the hobbyist literature on this species is sparse. Rasbora in the broad sense are typically silvery to pale olive on the flanks, often with a lateral stripe or midlateral band of varying intensity; whether R. hobelmani bears a distinct stripe or spot pattern is not confirmed in the available sources.
Habitat
FishBase places Rasbora hobelmani in pools of small upland streams, occupying the midwater to surface zone — a niche shared by many small stream rasboras of mainland Southeast Asia. Its native range spans eastern Myanmar and northern Thailand within the upper Mekong drainage, with the type locality in Chiengmai Province, an area of hilly terrain where watercourses run through forest before descending to the lowland plain.
Upland stream habitats in this region are typically clear to lightly tannin-stained, with moderate current in riffles easing to calmer pools where small cyprinids congregate. Water temperatures at altitude are somewhat cooler than in lowland rivers, and the chemistry is generally soft to moderately hard depending on local geology. The species is listed with a tropical climate profile and high resilience on FishBase.
Feeding
Rasbora are micro-predators and omnivores across the genus. In the wild, species like R. hobelmani are understood to feed on small insects and their aquatic larvae, zooplankton and small crustaceans taken at the surface and in the water column, supplemented with organic detritus and occasionally plant matter.
In captivity, rasboras of this type accept standard small-particle foods readily: quality flake, micro-pellets, and live or frozen fare such as daphnia, brine shrimp nauplii and chironomid larvae. Feeding at or near the surface suits the upturned-to-terminal mouth typical of Rasbora.
Mating
Rasbora hobelmani, like virtually all members of the genus Rasbora and the broader danionin clade, is an egg-scattering, non-guarding spawner. No nest is built and no parental bond forms. A receptive male closely pursues a gravid female through vegetation or over the substrate; at the climax of the chase the pair press together briefly and release eggs and milt simultaneously.
The eggs are adhesive to weakly adhesive and settle among fine-leaved plants, moss or gravel, where they are left entirely to develop without parental attendance. Adults will consume eggs they encounter, so in a breeding setup separation from the eggs is necessary.
Breeding
Captive breeding records for Rasbora hobelmani are not documented in the accessible literature, but the species can be expected to follow the standard rasbora egg-scattering protocol given its close relationship to better-known congeners. A separate, shallow spawning tank furnished with fine-leaved plants, java moss or a spawning mesh is the recommended approach, allowing eggs to fall out of reach of the adults.
Soft, slightly acidic water — around pH 6.5 and 79 °F — mirrors the soft upland stream conditions of the type locality and is consistent with conditions that trigger spawning in related rasboras. After spawning the adults should be removed; eggs typically hatch within two to three days and larvae become free-swimming a few days later, taking infusoria initially and then micro-foods and baby brine shrimp as they grow.
In the aquarium
Rasbora hobelmani is rarely encountered in the aquarium trade and is likely available only through specialist importers or hobbyists with access to wild-collected fish from the northern Thailand or Myanmar region. Its modest size (to 2.5 in) and shoaling instinct make it suited to a well-planted community aquarium with peaceful, similarly sized companions.
As an upland stream species it should do well in clear, moderately soft water in the range of roughly 75–81 °F (75–81 °F), with pH kept in the 6.5–7.5 band. Good oxygenation and gentle flow replicate the pool environment of small hill streams. A group of at least six will bring out natural shoaling behaviour and reduce shyness. This is a species for the patient specialist rather than the mass-market fishkeeper.
Conservation
Rasbora hobelmani has not been assessed by the IUCN Red List and carries a status of Not Evaluated (NE). The species' range in eastern Myanmar and northern Thailand places it within watersheds that face general pressures from deforestation, agricultural expansion and water extraction across mainland Southeast Asia, though upland stream habitats in northern Thailand retain better forest cover than many lowland areas.
Its restricted known range and infrequency in collections suggest that population data are inadequate for a formal assessment. Given the pace of habitat change across the upper Mekong region, targeted surveys of small upland cyprinids, including R. hobelmani, would be a useful conservation priority. The species is not commercially important and does not feature significantly in the aquarium trade.