Taxonomy & naming
Discherodontus ashmeadi was originally described as Barbus ashmeadi by the American ichthyologist Henry Weed Fowler in 1937, based on material collected from Khemmarat, Ubon Ratchathani province, in northeastern Thailand on the Mekong. The parenthetical authority in the current combination reflects the subsequent generic transfer.
The genus Discherodontus was erected by Tyson Roberts in 1989 to accommodate a cluster of medium-sized Southeast Asian barbs defined by the possession of two rows of pharyngeal teeth rather than the three rows found in related taxa. GBIF records the basionym as Barbus ashmeadi Fowler, 1937, and WoRMS confirms Discherodontus ashmeadi (Fowler, 1937) as the accepted combination. The Catalog of Fishes (Eschmeyer, CAS) is the governing authority for the valid name, which remains in Discherodontus. The species should not be confused with the old catch-all genus Puntius, from which many Asian barbs were separated in the early twenty-first century; Discherodontus was already a distinct genus before that broader revision.
Morphology
Discherodontus ashmeadi is a moderately large barb, reaching a standard length of 4.5–5.5 in, with some trade sources citing up to 5.5 in total length. It has the streamlined, somewhat fusiform body typical of riverine cyprinids adapted to fast-flowing water, rather than the deep, compressed form of smaller pool-dwelling barbs.
The common name "redtail barb" points to the species' most distinctive feature: vivid reddish or orange pigmentation on the caudal fin and, to varying degrees, on the other fins. The body is silvery to brassy, and sexual dimorphism follows the pattern typical of barbs — females become visibly fuller across the abdomen when gravid, while males tend to be trimmer and may show more intense fin colouration.
Habitat
The species inhabits clear, fast-flowing minor rivers and forest streams within the middle Mekong and Mae Klong drainages, ranging across northeastern Thailand, Laos, and Cambodia. The type locality is Khemmarat on the Mekong in Ubon Ratchathani province. Seriously Fish describes the habitat as clear fast-flowing water with thick marginal vegetation, leaf litter, submerged roots, and a substrate of boulders, stones, sand, and gravel with accumulations of decomposing plant material.
The species shows pronounced diel habitat use: individuals are active during daylight in deeper, faster-flowing sections of rivers, retiring to shallower, quieter areas at night. Water chemistry across its range is soft to moderately hard, with recorded values of 73–79 °F, pH 6.0–7.5, and hardness roughly 36–215 ppm. FishBase characterises it as a benthopelagic species preferring pools with leaf litter, consistent with the patchy, discontinuous populations documented in the field.
The IUCN notes that the species is a full migrant within the Mekong system, implying some seasonal movement along river corridors as part of its life history.
Feeding
Discherodontus ashmeadi is a carnivore of small aquatic and terrestrial invertebrates. FishBase and Seriously Fish document a diet that encompasses chironomid (midge) larvae, Daphnia, and similar crustaceans, as well as biofilm grazing from hard surfaces such as boulders and submerged roots.
In the aquarium the species accepts a varied diet of live and frozen invertebrates — bloodworm, brine shrimp, daphnia — along with quality prepared foods. The biofilm-grazing component of its diet in the wild suggests that some vegetable matter or algae-based foods are a worthwhile supplement. Offering variety helps maintain condition and colouration.
Mating
Like all barbs, Discherodontus ashmeadi is an egg-scattering, non-guarding spawner. No nest is constructed, no pair bond is formed beyond the spawning act itself, and no territory is held persistently. During courtship a driving male pursues a gravid female through vegetation or along the substrate of fast water, pressing alongside her briefly as eggs and milt are released simultaneously.
Colour and activity intensify in spawning-ready fish. The eggs, once scattered, receive no further attention from either parent; in the wild, current, leaf litter, and the interstices of gravel and root masses provide the incubation environment. The IUCN notes the species as a full migrant in the Mekong system, suggesting that spawning aggregations may occur in specific sections of the river at seasonal peaks linked to water temperature and flow regime.
Breeding
Discherodontus ashmeadi has rarely been bred in captivity relative to more commonly traded barbs, and detailed aquarium breeding accounts are sparse. By analogy with other medium-to-large riverine barbs, spawning would require soft to moderately hard, well-oxygenated water with some current, elevated temperature as a trigger, and a substrate of fine gravel or spawning mops to receive adhesive eggs.
Adults should be removed after spawning to prevent egg predation — a near-universal requirement for barbs, which show no parental care of any kind. Larvae are expected to be free-swimming within a few days of hatching and would initially require fine live foods such as infusoria or newly hatched brine shrimp nauplii. The species' migratory nature in the wild hints that replicating seasonal cues (water temperature fluctuation, changes in flow or water chemistry) may be important for reliable spawning in captivity.
In the aquarium
Discherodontus ashmeadi is an uncommon species in the hobby, appearing occasionally through specialist importers. Seriously Fish advises keeping it in groups of at least six individuals, as it is a shoaling species whose behaviour and security depend on conspecific company. Smaller groups lead to stress and increased vulnerability to disease.
The species demands high dissolved oxygen and moderate to strong water movement, reflecting its native fast-flowing river habitat. Weekly water changes of 30–50% are recommended to maintain water quality. It is noted as sensitive to shipping trauma and scale loss, so careful acclimatisation after import is important. Water parameters should reflect its native range: 73–79 °F, pH 6.0–7.5, hardness in the soft-to-moderate range. A spacious tank with a current, open swimming lanes, and some cover of submerged wood, leaf litter, and robust planting suits the species well. Given its medium-to-large adult size, tankmates should be chosen to match — robust, similarly active species that can hold their own in flowing water.
Conservation
Discherodontus ashmeadi is assessed as Least Concern (LC) on the IUCN Red List, with a population trend recorded as stable as of the April 2020 assessment (version 2025-2). The species has a moderately broad range across the middle Mekong and Mae Klong drainages and is not currently considered to face major threats driving population decline at a range-wide level.
Nonetheless, the Mekong basin faces escalating anthropogenic pressure: large-scale hydropower development on the mainstem and tributaries disrupts the migratory corridors on which species like D. ashmeadi depend, while deforestation in riparian zones degrades the clear, shaded stream habitats it favours. Pollution from agriculture and expanding urban areas is an additional concern across the Thai, Lao, and Cambodian portions of its range. The species is not listed on CITES. Ongoing monitoring of Mekong basin fish assemblages will be important given the pace of infrastructure development in the region.