Taxonomy & naming
Clarias leiacanthus was described by the Dutch ichthyologist Pieter Bleeker in 1851. It belongs to the family Clariidae, the airbreathing or "walking" catfishes, and to the genus Clarias, which spans dozens of species across Africa and Asia. The Catalog of Fishes treats Clarias leiacanthus as the valid name, and no other genus placement is in current use for this species.
The genus name Clarias derives from a Latin/Greek root referencing the fish's lively, vigorous movement out of water — a nod to the family's famous ability to survive and travel on land. The epithet leiacanthus is built from the Greek leios ("smooth") and akantha ("spine" or "thorn"), describing the smooth-edged pectoral spine that distinguishes this species from Clarias relatives with coarsely serrated spines. The name Clarias cataractus is treated as a synonym of this species in Eschmeyer's Catalog of Fishes.
Morphology
Like all Clarias, this species has the unmistakable walking-catfish body plan: a long, cylindrical, scaleless trunk, a flattened bony head, four pairs of barbels around the mouth, and a long-based dorsal fin that runs most of the length of the back, mirrored by a similarly long anal fin. The skin is naked and mucus-covered rather than scaled or plated.
A pair of stiff, locking pectoral spines sits at the leading edge of each pectoral fin; in this species the spine is comparatively smooth-edged (leiacanthus, "smooth spine") rather than heavily serrated, but it still locks rigid and can be jabbed defensively. Reported maximum size is about 13 in total length (FishBase), which is a genuinely large fish for a home aquarium — this is not a species that stays small.
Habitat
Clarias leiacanthus is native to Southeast Asia, recorded from the islands of Sumatra and Borneo. Clariids in this region typically inhabit slow-flowing rivers, swamps, flooded forest, rice paddies and other seasonally oxygen-poor freshwater habitats, and this species is described as a facultative air-breather — it can rely on gill respiration in well-oxygenated water but switches to gulping atmospheric air through an accessory breathing organ when dissolved oxygen drops, as it does in stagnant swamp pools and during the dry season.
This accessory air-breathing organ, shared across the family, is what allows Clarias to survive in water too poor in oxygen for most other fish, and to move overland between drying pools using its stiff pectoral spines and muscular body — the origin of the "walking catfish" name applied to the genus.
Feeding
Clarias leiacanthus is a nocturnal predator and opportunistic scavenger, consistent with the genus. In the wild it takes fish, aquatic invertebrates, crustaceans and other animal prey small enough to swallow whole, hunting mostly after dark. Any fish or invertebrate that fits in its mouth is at risk.
In captivity or aquaculture it readily accepts whole fish, prawn, pellets and other large meaty foods. Because it is a sizeable predator, tankmates must be too large for it to swallow — small fish and invertebrates housed with it should be expected to disappear.
Mating
Dedicated courtship and spawning behaviour for Clarias leiacanthus specifically is not well documented in the available literature; data is sparse for this species. Clariids in general pair up over open substrate or vegetation during the breeding season, often triggered by seasonal flooding and rains, with little courtship display beyond brief chasing and positioning before eggs are released and fertilised externally.
As with most large, commercially significant Clarias species, natural pairing and spawning in captivity is rarely observed or relied upon; production instead uses controlled hormone-induced spawning (see Breeding).
Breeding
Clarias leiacanthus is a large, commercially farmed catfish, and like other sizeable Clarias it is essentially not bred in the home aquarium. Across Southeast Asia, Clarias species of this kind are propagated at aquaculture scale using hormone-induced spawning — injecting mature broodstock with pituitary extract or synthetic hormones to trigger ovulation, then stripping eggs and milt for artificial fertilisation — rather than through natural pairing in a tank.
This species grows too large and is too poorly suited to aquarium conditions for hobbyist breeding to be a realistic goal. Anyone keeping it should expect a farmed or wild-collected fish, not a species with an established aquarium spawning protocol.
In the aquarium
Clarias leiacanthus is not a beginner community fish. Adults reach around 13 in total length, and most home aquariums are simply too small to house one long-term — this is a species best appreciated in public aquaria, large ponds, or left to the aquaculture trade it is actually farmed for. Anyone offered a small juvenile should plan for the adult size from day one.
Because its skin is scaleless, it is medication-sensitive: copper-based treatments and many standard medications should be dosed conservatively, often at reduced strength, as is generally advised for scaleless catfish. Its pectoral spines lock rigid and can jab the keeper or snag a net, so it should be moved in a container rather than netted. As a facultative air-breather it will make regular trips to the surface to gulp air and needs an air gap rather than a sealed lid. It is nocturnal and predatory, eating any tankmate small enough to swallow, and — like other Clarias — it is a well-known invasive species outside its native range, so it must never be released into local waterways.
Conservation
The IUCN Red List assesses Clarias leiacanthus as Least Concern, with the assessment dated 2018. It is a widespread species across its Sumatran and Bornean range and is not currently considered at risk.
The genus Clarias as a whole is hardy, adaptable and commercially farmed across much of Southeast Asia, which generally reduces pressure on wild populations for food-fish species like this one; specific threats to Clarias leiacanthus are not flagged in the sources reviewed here.