Taxonomy & naming
Hypselobarbus bicolor was described in 2016 by Knight, Rai, d'Souza, Philip and Dahanukar in Zootaxa (volume 4184, issue 2, pages 316–328), with the type locality given as the Sita River in Karnataka, on the western slope of the Western Ghats. The holotype was collected from that river, and the species is known to be endemic to the Western Ghats of India.
The genus Hypselobarbus is itself endemic to the Western Ghats and adjacent peninsular India — a lineage of large-bodied barbs that had long been absorbed into the sprawling catch-all genus Puntius but were progressively recognised as a distinct group. The description places H. bicolor close to H. pulchellus, from which it was distinguished by lateral-line scale counts (34–36 pored scales plus one to two additional scales), the number of barbels (two pairs), and molecular data. The Catalog of Fishes records the valid combination as Hypselobarbus bicolor Knight, Rai, d'Souza, Philip & Dahanukar, 2016.
Morphology
H. bicolor is a large barb with the deep-bodied, laterally compressed build typical of Hypselobarbus. The lateral line is complete, carrying 34–36 pored scales followed by one to two additional pored scales on the caudal fin base. Two pairs of barbels are present, as in the rest of the genus. The body is dark grey dorsally, shading to a paler ground with an ill-defined silver to bronze band running along the flank — the two-tone pattern that inspired the epithet bicolor.
Males in breeding condition develop small tubercles on the snout tip, a sexually dimorphic character noted in the original description. As with other members of the genus, the fish reaches a large adult size relative to typical aquarium barbs, though precise maximum recorded length data are not yet published for this recently described species.
Habitat
Like other Hypselobarbus species, H. bicolor occupies rivers and streams of the Western Ghats, preferring clear, fast-flowing and well-oxygenated water in the middle and upper reaches of river systems. The type locality, the Sita River in Karnataka, is a typical Western Ghats hill river with rocky and boulder-strewn substrate, good current, and high dissolved oxygen.
Congeners in the genus (such as H. jerdoni) are documented in water temperatures of roughly 68–79 °F and pH near neutral to slightly acidic (6.5–7.5), consistent with the cool, clear conditions of mid-elevation Western Ghats rivers. The genus has also been recorded in reservoirs across the Western Ghats states of Kerala, Karnataka, Tamil Nadu and Maharashtra, suggesting some tolerance for impounded water, but natural habitats are lotic and fast.
The Sita River drains the western slope of the Ghats into the Arabian Sea — a short, steep catchment typical of the region's river systems, where the monsoon drives seasonal flood pulses of considerable force.
Feeding
No published feeding study specific to H. bicolor exists. Based on the ecology of the genus and the habitat type, it is expected to be an opportunistic omnivore with a substantial detritivorous component: feeding on organic debris, leaf litter, periphyton (algae and associated micro-organisms scraped from rock surfaces), and invertebrates including insect larvae and small crustaceans. Congener H. jerdoni is documented feeding in this manner in fast-flowing rocky streams.
In an aquarium setting, members of Hypselobarbus accept a broad diet of high-quality sinking pellets and wafers, supplemented with live or frozen foods such as bloodworm and Daphnia, and some vegetable matter or blanched vegetables to reflect the detritivorous and algal elements of the natural diet.
Mating
H. bicolor, like all barbs, is an egg-scattering, non-guarding spawner. No published account of courtship behaviour for this species exists, but the pattern shared across Hypselobarbus and the wider Cyprinidae is well-established: a driving male pursues a gravid female over the substrate or among vegetation, and eggs and milt are released together without any nest construction or pair bond beyond the spawning act itself.
Large riverine barbs in this group are typically seasonal broadcast spawners whose reproductive activity is tied to monsoon flood cycles, when rising water levels and temperature changes trigger migration to spawning grounds over gravel or rocky substrate. Males in breeding condition, as noted for H. bicolor, develop snout tubercles that may play a role in courtship contact.
Breeding
No captive breeding record for H. bicolor has been published. By analogy with other large Hypselobarbus species, controlled breeding in aquaria or aquaculture facilities would require substantial space, well-oxygenated and fast-flowing water, a rocky or gravel spawning substrate, and a seasonal temperature or photoperiod cue to simulate monsoon-onset conditions. Eggs would be scattered freely and receive no parental attention; adults removed after spawning would prevent predation of the spawn.
Given the species was described only in 2016, it remains poorly studied in captivity. Its large adult size places it outside the scope of standard aquarium husbandry for most hobbyists, and no commercial breeding programme is on record.
In the aquarium
H. bicolor is a large Western Ghats barb that is not established in the ornamental trade and is essentially unknown in hobbyist collections. Should it become available, the requirements of the genus apply: a very large tank with powerful filtration and a strong current, cool-to-moderate water temperature (around 68–79 °F), near-neutral pH, and hard rocky substrate or smooth cobbles to reflect the fast-flowing hill-stream habitat. The species is not suitable for general community aquaria.
Congeners kept by specialist hobbyists (such as H. jerdoni) confirm the need for high dissolved oxygen, steady current, and open swimming space. Their behaviour in groups is active but generally non-aggressive toward other robust fishes. A diet of sinking pellets, live and frozen invertebrates, and vegetable matter keeps them in good condition.
Conservation
H. bicolor has not been assessed for the IUCN Red List; described only in 2016, no formal evaluation had been completed at the time of writing. However, the wider context of Western Ghats freshwater biodiversity is one of serious concern: the Ghats are a global biodiversity hotspot whose freshwater fish fauna faces mounting pressure from hydroelectric dams, water extraction for agriculture and urban use, pollution from agricultural runoff, sand mining in riverbeds, and the introduction of exotic species.
Several Hypselobarbus species with comparably restricted ranges in the Western Ghats have been assessed as Vulnerable or Endangered by the IUCN. H. bicolor, as an apparent endemic of the Sita River basin or a limited set of adjacent drainages, is potentially exposed to the same threats. The Sita River, like many short western-slope rivers draining the Ghats, is under pressure from catchment deforestation and seasonal water scarcity during the dry months. Formal range surveys and a Red List assessment are warranted.