Taxonomy & naming
Tachysurus ussuriensis was described by Johann Friedrich von Brandt in 1861. Current ichthyological treatments place this fish in the genus Tachysurus, as Tachysurus sinensis (Lacepède, 1803) — the Bagridae have been heavily reshuffled by molecular work, and older aquarium and fisheries literature under the name "Tachysurus ussuriensis" refers to the same species now carried under Tachysurus. This article keeps the name Tachysurus ussuriensis, the combination under which the species is commonly known in aquarium and older fisheries sources.
The family Bagridae (bagrid catfishes) is a large Asian and African group that also includes Mystus, Hemibagrus, Bagrichthys and Sperata in Asia, and Bagrus proper in Africa. The species epithet sinensis is Latin for "of China", reflecting its wide native range across East Asia.
This fish was long listed as Bagrus sinensis; Eschmeyer's Catalog of Fishes now treats that name as a synonym of Tachysurus ussuriensis, the valid name followed here.
Morphology
This is a robust, elongate bagrid with a broad head, a wide mouth armed with bands of small teeth, and four pairs of barbels typical of the family, used to feel out prey along the riverbed at night. The body is scaleless, with smooth naked skin rather than the bony plating seen in some other catfish groups. The dorsal and pectoral fins each carry a stiff, serrated spine that can be locked erect — a genuine hazard when handling the fish, since these spines readily snag a net and can jab the skin.
Maximum recorded size in the wild is 14 in standard length and about 3 kg in weight. Aquarium-trade juveniles are typically sold at around 3 in, which is a small fraction of the adult size — a classic case of a catfish that looks manageable in the shop but is not.
Habitat
Tachysurus ussuriensis is native to rivers, lakes and other freshwater systems across a broad swath of East and Southeast Asia, including China, Vietnam, Laos, Korea, Japan, India, and the Amur River basin shared with Russia; it has also been introduced to Germany. It is a demersal, non-migratory resident that spends most of its time near the bottom.
Unlike many tropical catfish, it is notably cold-tolerant, living naturally in temperate as well as subtropical waters and able to handle 61–77 °F without supplemental heating. It favours a moderate pH around 6.0–7.6 and is generally described as a hardy species with a wide tolerance for water conditions, rather than a fish tied to a narrow chemistry.
Feeding
This is a nocturnal predator that hunts by scent and touch after dark, taking fish, invertebrates and other animal prey it can overpower and swallow — anything smaller than itself is at risk, and this must shape any stocking plan around it.
In captivity it accepts large meaty foods readily: whole or chopped fish, prawn, and sinking pellets or carnivore-formulated foods. It is not a fussy feeder, but portions and tankmates both need to scale with its eventual size — it will not stay a small fish for long, and anything that fits in its mouth is a potential meal, not a companion.
Mating
Reported courtship and pairing behaviour is not well documented for this species outside commercial hatcheries. In males, an elongate genital papilla in front of the anal fin distinguishes the sexes.
In nature and in unmanaged culture ponds, natural spawning is reported not to occur reliably; commercial hatcheries do not rely on courtship taking its course in ordinary grow-out tanks, and instead condition and inject broodstock outside the display system entirely.
Breeding
Tachysurus ussuriensis is a farmed, commercially important food fish in China, reaching market weight of roughly 120–180 g in about two years of pond culture, and its reproduction is managed accordingly: natural spawning does not occur in captivity, and hatcheries induce spawning with exogenous hormones (hCG, LHRH and CPE combinations, sometimes in combination). Selective and cross-breeding programmes, including crosses with Pelteobagrus (Tachysurus) vachelli and genetic all-male lines exploiting the roughly 30% faster growth of males, are used to improve production traits.
This is squarely a hormone- and hatchery-bred species at commercial aquaculture scale, not a fish that spawns in a home aquarium. No home-aquarium breeding is documented, and given its adult size and reproductive biology, hobbyists should not expect or attempt to breed it outside a dedicated pond or hatchery setup.
In the aquarium
Buy this fish with its adult size firmly in mind: it reaches roughly 14 in and several kilograms in the wild, and even aquarium-conditioned fish grow well beyond the 3 in juvenile size sold in stores. A large juvenile can be kept for a while in a substantial aquarium, but an adult genuinely needs pond-scale or public-aquarium-scale housing — most home tanks cannot hold this fish long-term, and it should not be bought on impulse as a "catfish for the community tank."
Its scaleless skin makes it more sensitive than scaled fish to copper-based medications and some treatments generally, so dose conservatively if treatment is ever needed. The locking, serrated dorsal and pectoral spines snag nets and can jab the handler, so move it in a soft container rather than netting it. It is nocturnal and appreciates cover to retreat to by day, and its cold tolerance (61–77 °F) means it does not require a heater, but it must never be housed with fish small enough to swallow — that includes almost anything under community-tank size once it matures.
Conservation
The IUCN Red List assesses this species as Least Concern. It is common and widespread across its native range, is a significant aquaculture and commercial fisheries species in China and neighbouring countries, and faces no documented major conservation threats.
Its abundance is bolstered rather than threatened by its economic importance — it is intensively farmed, and wild populations do not appear to be under meaningful collection or habitat pressure at present.