Taxonomy & naming
Dawkinsia rohani was formally described by Rema Devi, Indra and Knight in 2010, originally under the genus Puntius — then the standard repository for most small South Asian barbs. In the trade it was also marketed as Barbus rohani, a name that predates the post-2012 reclassification and is now considered a synonym. The valid current combination, Dawkinsia rohani (Rema Devi, Indra & Knight, 2010), reflects the revision of the South Asian barb complex by Pethiyagoda and colleagues (2012), who dismembered the old polyphyletic Puntius into several better-supported genera. Dawkinsia was erected to contain a group of Indian and Sri Lankan species sharing a suite of morphological and osteological characters, and D. rohani was assigned to it accordingly.
The genus name Dawkinsia honours the British evolutionary biologist Richard Dawkins. The specific epithet rohani honours Rohan Pethiyagoda, the Sri Lankan ichthyologist whose work on South Asian freshwater fishes has been foundational for the modern understanding of the subcontinent's cyprinid diversity. The parenthetical authority in the binomial reflects that the species was originally placed in a different genus when first described. FishBase and the Catalog of Fishes list the species under the subfamily Smiliogastrinae within the family Cyprinidae.
Morphology
Dawkinsia rohani is a moderately sized barb: FishBase records a maximum of 3.5 in standard length, while trade sources give 3–4.5 in total length, suggesting the fish can exceed 3.5 in in well-kept aquaria. The body is laterally compressed and somewhat deep, a shape typical of the genus, with large scales and a relatively large eye.
The species belongs to a genus in which members commonly display orange or red fins and a dark lateral stripe or series of blotches, though the precise colour pattern of D. rohani in life is not extensively documented in the hobby literature available. As is consistent with most Dawkinsia, sexual dimorphism is expressed primarily in body depth and fullness: females become noticeably rounder in the abdomen when gravid, while males tend to be slimmer and may show more intense fin colour during spawning condition.
Habitat
Dawkinsia rohani is known exclusively from the hill streams of Kanyakumari District, the southernmost district of Tamil Nadu and the tip of the Indian peninsula, in drainages that flow west to the Arabian Sea. This is the extreme southern end of the Western Ghats, one of the world's recognised biodiversity hotspots, where hill streams run through laterite and granite terrain at elevation before descending to a narrow coastal plain.
The species inhabits fast-moving, well-oxygenated water typical of Western Ghats hill streams — clean, clear, moderately cool and near-neutral. Data from the hobby (Seriously Fish) indicate a temperature around 72 °F, a pH of approximately 6, and soft water (around 107 ppm hardness). Such conditions reflect the character of these monsoon-fed streams: high seasonal variation in flow, cool temperatures fed by elevated catchments, and low dissolved solids. The species is described as benthopelagic and schools in the water column rather than holding to the bottom.
Feeding
Dawkinsia rohani is an omnivore. In common with most Western Ghats barbs of its size and body form, it feeds opportunistically on the range of food items available in hill-stream environments: aquatic and terrestrial invertebrates including worms, insect larvae and crustaceans, along with plant matter, algae and organic detritus. Seriously Fish characterises the species as taking worms, insects and crustaceans alongside plant material — a typical barb diet that reflects both the productivity and the seasonal fluctuation of Western Ghats hill streams.
In the aquarium, the species is straightforward to feed and should accept a varied diet of good-quality dry foods (flakes, small pellets) supplemented with live and frozen invertebrate foods such as bloodworm, daphnia and brine shrimp, along with some vegetable or plant-based components.
Mating
Like all barbs, Dawkinsia rohani is an egg-scattering, non-guarding spawner. There is no nest construction, no territorial pair bond, and no parental care at any stage. Courtship involves driving behaviour in which a ready male pursues a gravid female through the water column and among any available vegetation or substrate structure, pressing close to her as eggs and milt are released simultaneously.
Spawning readiness in the wild is likely triggered by seasonal cues — changes in temperature, day length or water chemistry associated with monsoon inflow — as is typical for hill-stream barbs of peninsular India. The eggs are adhesive and settle among plants, roots or substrate detritus after release. Adults that remain in the spawning area will consume eggs, a behaviour common to the family and a strong selection pressure for rapid dispersal of eggs in flowing water.
Breeding
Dawkinsia rohani is not widely bred in captivity and reports in the hobby literature are sparse, though the species should follow the general pattern for Dawkinsia and related Western Ghats barbs. Breeding can be encouraged in a separate aquarium with soft, slightly acidic, clean water at around 72 °F, fine-leaved plants or spawning mops, and a mesh or glass-bead layer over the bottom to protect eggs from being eaten by the adults after spawning.
A well-conditioned pair or small group is introduced in the early evening; spawning typically takes place in the morning. Females may deposit several hundred small adhesive eggs in a single session. Adults should be removed immediately after spawning. Eggs hatch in approximately 24–48 hours at appropriate temperatures, and the larvae become free-swimming a few days later, initially requiring infusoria or very fine first foods before graduating to newly hatched brine shrimp nauplii. The restricted availability of wild-caught specimens makes the development of reliable captive-breeding protocols valuable for the conservation of this Vulnerable species.
In the aquarium
Dawkinsia rohani is an uncommon species in the hobby — it appears occasionally in specialist trade (Aquarium Glaser has offered it) but is not a standard item. It is a peaceful, schooling fish best kept in a group of six or more with other active, non-aggressive species of similar size. Seriously Fish describes it as suited to a riverine community aquarium, and its intolerance of organic pollutants means that excellent filtration and regular water changes are non-negotiable.
The tank should provide clean, well-oxygenated, moderately flowing water at around 72 °F, a pH near neutral to slightly acidic, and soft to moderately soft water — parameters reflecting its hill-stream origins. Good flow and high dissolved oxygen are important; stagnant or fouled water will cause rapid decline. The species is omnivorous and undemanding in its food requirements, accepting most standard aquarium foods readily. Because it is endemic to a very small range and assessed as Vulnerable, hobbyists keeping this species should seek captive-bred stock wherever possible and consider participating in records of captive populations.
Conservation
Dawkinsia rohani is assessed as Vulnerable (VU) on the IUCN Red List under criterion D2, reflecting an extremely restricted area of occupancy estimated at approximately 6 mi². The species is a strict endemic to the hill-stream drainages of Kanyakumari District at the southern tip of Tamil Nadu — an area that represents one of the most confined natural ranges of any described Indian barb. The assessment dates from 2016.
Threats to this species follow the pattern affecting much of the Western Ghats freshwater fauna: agricultural runoff, damming and water extraction from hill streams, sand mining, and the spread of invasive species. The monsoon-fed hill streams of Kanyakumari District are under pressure from the region's growing population and expanding agriculture. Collection for the aquarium trade adds a further potential pressure on a population already constrained to a tiny geographic footprint. Because the species is intolerant of organic pollutants, any deterioration in water quality in its native streams poses a direct threat. Conservation of D. rohani is effectively inseparable from the protection of the remaining intact hill-stream habitat in this corner of the Western Ghats.