Taxonomy & naming
Tachysurus analimaculatus was described in 2026 by Weihan Shao and E Zhang, in a joint paper with Xingwei Cai and Tan Duc Nguyen published in the journal Animals, as part of a wholesale revision of Tachysurus virgatus (Oshima, 1926). That nominal species had long been recorded across a nearly 2,0 mi stretch of coastal south China and northern-central Vietnam, but integrative work combining mitochondrial DNA (cytochrome b and COI) with detailed morphometrics showed the name covered ten distinct, non-interbreeding lineages sharing near-identical body plans — a textbook case of cryptic diversity in a morphologically conservative bagrid catfish. True T. virgatus turned out to be restricted to a single river on Hainan Island; the other nine populations, including this one, were described as new species in the same paper.
T. analimaculatus belongs to the genus Tachysurus, family Bagridae, and within that genus to the informally named "T. virgatus species group" — twelve species (three previously known, nine new) united by a monophyletic mitochondrial lineage and, in most members, a coloration of two continuous black longitudinal stripes running from head to tail. Within the group it sits in Clade II alongside T. kyphus and T. qiongzhouensis, its nearest phylogenetic relative, from which it differs by 1.9–2.7% in cytochrome b sequence divergence despite being difficult to tell apart on external appearance alone.
The holotype (GUANGZ37486, 2.85 in standard length) was collected by Weihan Shao in March 2020 from the Beijiang River at Zhongluotan Town, Guangzhou City — a tributary of the Pearl River in Guangdong Province. Paratypes came from the same site and from the Xijiang River near Guigang City in the Guangxi Zhuang Autonomous Region, another Pearl River tributary. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) lists Tachysurus analimaculatus Shao & Zhang, 2026 as the currently valid name; there are no synonyms.
Morphology
Tachysurus analimaculatus is a striped Tachysurus in the sense used by its describers: two continuous black longitudinal stripes run along the flanks from the head to the caudal peduncle, set against a paler ground color, with three pairs of barbels (one long maxillary pair, two shorter mandibular pairs) typical of the genus. The caudal fin is deeply forked, with narrow lobes and a prominent notch in the dorso-lateral stripe just behind the dorsal fin — a combination shared with several close relatives (T. bailongensis, T. pseudovirgatus, T. trimaculatus and T. furcatus).
What separates T. analimaculatus from those species is a mid-lateral stripe that is constricted, irregular and tapers posteriorly rather than running uniform and unbroken, and a comparatively slender body — depth at the anus measured at 13.8–19.2% of head length, versus 19.1–24.5% in its two closest relatives, T. qiongzhouensis and T. sinovietnamensis. It also has a shorter nasal barbel (30.6–44.8% of head length) than T. qiongzhouensis and a more slender caudal peduncle than T. sinovietnamensis. The feature that gives the species its name is a prominent black blotch on the anal fin, a marking the describing authors singled out as diagnostic in the field.
Across the type series (holotype plus ten paratypes), standard length ranged from about 1.61 in to 3.43 in, giving a described maximum size of roughly 3.4 in SL. Like all Tachysurus, the skin is entirely scaleless, and the dorsal and pectoral fins carry a stiff, serrated, locking spine — a standard bagrid feature with direct handling implications (see "In the aquarium").
Habitat
Tachysurus analimaculatus is known only from the lower Pearl River basin of south China, with type specimens from the Beijiang River (Guangdong) and Xijiang River (Guangxi), both major Pearl River tributaries. The describing paper places it among the strict mainstem-river specialists of the T. virgatus group — one of three species (with T. qiongzhouensis and T. sinovietnamensis) confined entirely to the main channels of large rivers rather than the smaller streams many of its relatives favor.
The paper characterizes mainstem habitat in this group as slower-flowing water over finer sand or silt substrates with lower dissolved oxygen than the fast, gravel-and-boulder streams occupied by the group's stream specialists — a contrast the authors link to the deeply forked, narrow-lobed caudal fin shared by all the mainstem species, a shape associated in the literature with efficient cruising in slower, deeper water. No specific temperature or pH measurements are reported in the original description; the species' basin sits in the subtropical climate zone of coastal south China, but no numeric water-chemistry data have been published for T. analimaculatus specifically.
Feeding
No diet data have been published for Tachysurus analimaculatus — the 2026 description is a taxonomic and phylogenetic paper and does not report gut contents or foraging behavior. Like other Tachysurus, it is presumed, at the genus level, to be a nocturnal benthic feeder that forages along the riverbed for aquatic invertebrates, using its barbels to locate food by touch and taste after dark. This is a genus-level inference, not a species-specific finding.
Mating
No spawning behavior, seasonality or courtship has been documented for Tachysurus analimaculatus. Genus-level, other Tachysurus species are seasonal spawners with paired courtship and male-led nest preparation, but nothing about this species' reproductive biology has been reported and none should be assumed.
Breeding
Breeding biology is undescribed for Tachysurus analimaculatus. Presumed genus-level, Tachysurus species are cavity or sheltered-substrate spawners in which the male guards the eggs after fertilization, but this has not been confirmed for T. analimaculatus and the species has never been bred, or even kept, in captivity.
In the aquarium
Tachysurus analimaculatus is not in the aquarium trade. It was formally described only in 2026 from a handful of type specimens collected in the lower Pearl River basin, and no aquarium husbandry information exists for it. Any care notes here are necessarily genus-level and speculative, offered only as a starting point should the species ever become available: other small Tachysurus are generally peaceful, nocturnal bottom-dwellers that do best over a soft sand substrate with caves or pipe sections for daytime shelter, fed sinking foods after lights-out. The scaleless skin typical of the genus means increased sensitivity to copper-based medications, and the locking dorsal and pectoral spines mean the fish should always be moved in a container rather than a net. None of this has been verified for T. analimaculatus itself.
Conservation
Tachysurus analimaculatus has not been assessed by the IUCN Red List; it carries no formal conservation status. The describing authors, discussing conservation implications of their revision, grouped the strictly mainstem-dwelling species of the T. virgatus group — a category that includes T. analimaculatus — with those they recommend for a Least Concern designation, citing extents of occurrence in the range of roughly 5,000–30,0 mi² and no documented population decline for that group as a whole. This is the authors' own preliminary recommendation, not an official IUCN listing, and no species-specific population or threat data have been published for T. analimaculatus.
More broadly, the paper notes that recognizing this cryptic diversity matters for conservation: species that were effectively invisible while lumped into a single wide-ranging "T. virgatus" can now be assessed and, if warranted, protected individually. The Pearl River basin, where T. analimaculatus lives, is one of the most heavily developed river systems in China, though no specific habitat-loss data for this species have been reported.