Taxonomy & naming
Tachysurus furcatus was described in 2026 by Weihan Shao and E Zhang, with co-authors Xingwei Cai and Tan Duc Nguyen, in a paper published in the journal Animals that used combined molecular and morphological evidence to split the nominal species Tachysurus virgatus (Oshima, 1926) into ten distinct species across coastal south China and central-northern Vietnam. Populations that looked essentially identical externally turned out to represent separately evolving lineages, isolated from one another by the region's many independent coastal drainage systems.
T. furcatus belongs to Bagridae, genus Tachysurus, within the T. virgatus species group. It falls in Clade I of the group's phylogeny, forming a strongly supported sister pair with T. bailongensis of coastal Guangxi, China, from which it differs by only 1.5% in cytochrome b sequence despite occupying a different country and, per the describing authors, showing clear differences in body proportions and color pattern.
The holotype (GUANGP63012, 2.65 in standard length) was collected by Weihan Shao in June 2025 from the Nhat Le River, Quang Binh Province, central Vietnam — a coastal river draining into the South China Sea. Paratypes came from the same river. The species' full known distribution, per both the paper and the Catalog of Fishes, extends to the Hương River drainage in adjacent Thừa Thiên Huế Province. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) lists Tachysurus furcatus Shao & Zhang, 2026 as the valid name, with no synonyms.
Morphology
Tachysurus furcatus shows the striped Tachysurus pattern common to most of its species group: two continuous black longitudinal stripes from head to caudal peduncle, a deeply forked caudal fin with narrow, straight-edged lobes, and a prominent notch in the dorso-lateral stripe behind the dorsal fin. The mid-lateral stripe runs uniform and unconstricted along its length, as in its closer relatives (T. pseudovirgatus, T. virgatus, T. trimaculatus and T. bailongensis).
The diagnostic feature, and the source of its name, is the point where the mid-lateral stripe meets the operculum: in T. furcatus it splits into two or three short black lines that converge on the dark blotches on the gill cover, forming a visible fork — unlike the single continuous connection seen in T. trimaculatus and T. bailongensis, or the interrupted stripe origin of T. virgatus. It also has a notably deep caudal peduncle (59.5–71.1% of head length) compared with its close relative T. pseudovirgatus (42.1–45.3%).
Across the type series, standard length ranges from about 2.07 in to 2.89 in, giving a described maximum size of roughly 2.9 in SL. As in all Tachysurus, the skin is entirely scaleless, and the dorsal and pectoral fins carry a locking, serrated spine.
Habitat
Tachysurus furcatus is known from the Nhat Le River in Quang Binh Province and the Hương River in Thừa Thiên Huế Province, both coastal rivers of central Vietnam draining into the South China Sea. The describing authors classify it as one of the T. virgatus group's obligate stream specialists — recorded exclusively in flowing stream habitat rather than the slower river mainstems used by some of its relatives.
Stream-specialist habitat in this group is characterized in the paper as high-flow-velocity water over coarse gravel or boulder substrate with high dissolved oxygen, in contrast to the finer sand-and-silt, lower-oxygen mainstem channels used by the group's mainstem specialists. No temperature or pH data have been published specifically for T. furcatus; its native rivers lie in the coastal tropical-to-subtropical climate of central Vietnam.
Feeding
No diet information has been published for Tachysurus furcatus; the 2026 description is a taxonomic and phylogenetic study and does not record gut contents or foraging behavior. At the genus level, other Tachysurus are nocturnal benthic feeders that use their barbels to find invertebrate prey on the substrate after dark — a reasonable presumption, though not documented for this species.
Mating
No courtship or spawning behavior has been recorded for Tachysurus furcatus. Genus-level, Tachysurus species tend to be seasonal spawners with paired courtship, but nothing specific to this species has been reported.
Breeding
Breeding biology is entirely undescribed for Tachysurus furcatus. Presumed genus-level, Tachysurus are cavity or sheltered-substrate spawners with male egg-guarding, but this has not been confirmed for T. furcatus, which has never been kept or bred in captivity.
In the aquarium
Tachysurus furcatus is not in the aquarium trade. Described only in 2026 from stream habitat in central Vietnam, it has no husbandry record. Any care notes offered here are genus-level speculation for reference only: other small Tachysurus generally do well as peaceful, nocturnal bottom-dwellers, and this species' documented preference for fast, well-oxygenated, gravel-bottomed streams suggests it would need strong water movement and high dissolved oxygen if it were ever kept, rather than the still water many bottom-dwelling catfish tolerate. Because Tachysurus skin is naked and scaleless, the genus is generally more sensitive to copper-based medications than scaled fish, and the locking dorsal and pectoral spines call for moving fish in a container rather than a net. None of this is confirmed for T. furcatus specifically.
Conservation
Tachysurus furcatus has not been assessed by the IUCN Red List and carries no official conservation status. Unlike several of its closest relatives, it was not singled out for a specific proposed threat category in the describing paper's conservation discussion — the authors explicitly recommended Vulnerable status for T. trimaculatus and T. heterofasciatus, and Endangered status for T. platystomus and T. pseudovirgatus, but did not extend either recommendation to T. furcatus by name. Its distribution across two river drainages (Nhat Le and Hương) may make it somewhat less range-restricted than those single-locality species, but no dedicated population or range assessment has been published for it.
More broadly, the authors emphasize that resolving the T. virgatus group's cryptic diversity is itself a conservation contribution: populations that were previously invisible under one widespread species name can now be tracked and assessed individually rather than assumed safe by association with a broadly distributed nominal species.