Taxonomy & naming
Barbodes bunau was described by Rachmatika in 2005, with the type locality given as the Sebuku and Sesayap river drainages of North Kalimantan (Kalimantan Timur), Indonesian Borneo. The Catalog of Fishes (Eschmeyer, CAS) is the authority for the valid genus placement; the species is currently assigned to Barbodes, the Old World barb genus that was long used alongside the catch-all Puntius for Asian barbs.
Morphological study places B. bunau in association with B. lateristriga but distinct from the B. binotatus species group. It is not among the taxa reassigned in the large Pethiyagoda et al. (2012) revision of South and Southeast Asian barbs, having been described after that taxonomic flux began; its generic assignment in Barbodes reflects the current Catalog of Fishes position. Voucher material is held under catalog numbers CMK 9535.
The species epithet bunau is drawn from the Dayak Punan language — the vernacular word used by the indigenous Punan people of the Seturan watershed in East Kalimantan. The genus name Barbodes derives from Latin barbus (barbel) combined with Greek -oides (resembling), denoting a fish with barbels resembling the European barbels.
Morphology
Barbodes bunau is a small barb reaching a maximum recorded total length of approximately 2.5 in. Its body form is typical of the Barbodes lineage — moderately deep and laterally compressed, with the characteristic paired maxillary barbels of the genus. The common name "black ink barb" reflects a dark pigmentation pattern that sets it apart from close relatives such as B. binotatus.
The species is morphologically distinct from the B. binotatus group, and published material has illustrated specimens in the range of 8–11 in standard length range in referenced museum vouchers — likely referring to the voucher catalog (CMK 9535, 202 and 11 in), though FishBase confirms the live size at around 2.5 in total length. Detailed meristic counts and color pattern descriptions are available in the original 2005 description by Rachmatika. Sexual dimorphism, if present, has not been formally characterized in the available literature.
Habitat
Barbodes bunau is known from the Sebuku and Sesayap river systems of North Kalimantan, Indonesian Borneo — two drainages that flow northward through lowland tropical forest toward the Celebes Sea. The species is classified as benthopelagic, living in and near the substrate in freshwater environments.
Hobbyist sources describe its preferred habitat as clear to slightly murky waters with moderate current over sandy and rocky substrates with associated aquatic vegetation. These conditions are broadly consistent with the shaded forest streams and tributary systems typical of lowland Borneo, where water is generally warm (75–82 °F), soft to moderately hard, and slightly acidic to neutral (pH 6.0–7.0, GH approximately 5–12 dH). The species has not been recorded outside the two named drainages, suggesting a naturally restricted range even before accounting for habitat modification.
Feeding
Barbodes bunau is an omnivore in the manner typical of the genus. In its native lowland streams it likely exploits a combination of small invertebrates — insect larvae, microcrustaceans, worms — along with algae, biofilm, and organic detritus picked from sandy or rocky substrate and from the surface of submerged wood and vegetation. The benthopelagic lifestyle suggests active foraging through the lower water column and across the bottom.
Detailed dietary studies specific to this species have not been published. In aquarium conditions it can be expected to accept the range of foods taken by similar-sized omnivorous barbs: quality flake and small pellets as a staple, supplemented with live or frozen items such as bloodworm, brine shrimp, and daphnia, along with some plant or algae-based food.
Mating
Like all barbs, Barbodes bunau is an egg-scattering, non-guarding spawner. There is no nest, no bubble-nest, no mouthbrooding, and no parental care of any kind. When in spawning condition, a male pursues a gravid female through vegetation or over the substrate, the two coming together briefly while eggs and milt are released simultaneously.
Eggs are adhesive and fall among fine-leaved plants, onto sandy substrate, or into crevices between rocks and gravel where the parents make no further effort to tend them. The breeding season in the wild is not formally described for this species, but like most tropical lowland barbs it likely spawns opportunistically when water conditions are suitable, with rainfall and river-level fluctuations potentially acting as additional cues.
Breeding
No captive breeding accounts specific to Barbodes bunau are available in the published literature; the species is rare in the aquarium trade and most husbandry expectations are extrapolated from related Barbodes and Puntius barbs of comparable size. The general method for small egg-scattering barbs applies: a shallow, well-filtered spawning tank with soft, slightly acidic water (pH around 6.5, temperature 77–81 °F), fine-leaved plants or a spawning mop over a mesh or layer of marbles to protect eggs from the adults.
After a period of conditioning on varied live and frozen foods, a gravid female and one or more males can be introduced to the spawning tank. Spawning typically occurs in the morning. Adults should be removed promptly after spawning is complete, as they will consume eggs and early larvae. Eggs of similar small barbs hatch within one to two days, with larvae becoming free-swimming a few days later and ready for infusoria, followed by newly hatched brine shrimp. Successful captive breeding would support conservation awareness and reduce any pressure on wild populations.
In the aquarium
Barbodes bunau is rarely seen in the aquarium hobby; its restricted wild range in North Kalimantan and its Vulnerable status mean it does not appear in the mainstream ornamental trade. When encountered — primarily in specialist collections or among hobbyists with a particular interest in wild Bornean barbs — it can be kept under conditions suitable for other small, peaceful Barbodes species.
A tank of at least 23.5–31.5 in with good filtration, moderate flow, and areas of fine-leaved planting over sand or fine gravel would reflect the clear-to-slightly-murky stream habitats of its native drainages. Water should be kept warm (75–82 °F), soft to moderately hard, and slightly acidic to neutral (pH 6.0–7.0). As a shoaling species it should be kept in groups of at least six; it is reported to be peaceful and would suit a community of comparably sized, non-aggressive fishes. The common name "black ink barb" suggests distinctive dark markings that would make a well-lit shoal a visually striking display.
Conservation
Barbodes bunau is assessed as Vulnerable (VU) on the IUCN Red List, last evaluated in January 2019 under criteria B1ab(ii)+2ab(ii). These criteria reflect a restricted extent of occurrence and area of occupancy, with evidence of continuing decline in the quality or extent of its habitat — specifically the river systems of North Kalimantan, Indonesian Borneo.
The Sebuku and Sesayap drainages lie in a region of Borneo that has experienced extensive deforestation, expansion of oil palm plantations, coal mining activity, and associated sedimentation and water-quality degradation of lowland rivers and streams. A species known from only two river drainages has very limited ability to withstand such pressures, and the Vulnerable listing reflects the genuine uncertainty about how much suitable habitat remains accessible. No targeted conservation measures specific to this species are known. Its rarity in the aquarium trade means captive breeding programs have not yet been established as a buffer against wild population loss.