Taxonomy & naming
Pangasius macronema was described by the Dutch-German ichthyologist Pieter Bleeker in 1850 (some catalogs list the date as 1851, a minor variant in dating Bleeker's prolific output). It belongs to the family Pangasiidae, the shark catfishes, a group of schooling, torpedo-shaped Asian river catfishes that includes some of the largest freshwater fish in the world alongside smaller riverine species like this one.
The genus name Pangasius derives from a local Javanese or Sundanese vernacular name for these catfishes; the species epithet macronema combines Greek makros ("long") and nema ("thread" or "filament"), likely referencing an elongated barbel or filamentous fin ray noted in the original description. The Catalog of Fishes treats Pangasius macronema as the valid name, with the genus Pangasius unchanged by modern revisions of Siluriformes.
Morphology
Like other Pangasiidae, Pangasius macronema has the streamlined, laterally compressed, silvery body that gives the group its "shark catfish" name — a forked tail, a tall pointed dorsal fin with a single stiff spine, and a long adipose fin. The skin is scaleless and naked, smooth to the touch, a trait shared across the family and one that matters directly for aquarium care (see "In the aquarium").
FishBase reports a maximum size of about 12 in standard length, with a single dorsal spine, seven dorsal soft rays and a long anal fin of 30–38 soft rays typical of the genus. This makes it one of the smaller Pangasius species — modest by the standards of a genus that includes species exceeding a metre — but 12 in is still a substantial, active, fast-swimming fish that outgrows the vast majority of home aquariums.
Habitat
Pangasius macronema is native to Southeast Asia, recorded from the Mekong River mainstream and from the Kapuas River basin of Kalimantan, Indonesian Borneo. It is a freshwater species of large lowland rivers, where it forms schools in open water and, in the Mekong system, is understood to retreat to deep dry-season refuge pools along with other Pangasiidae during the low-water months.
Water in its native rivers is warm and only mildly mineralised: reported conditions are roughly 68–79 °F with pH around 6.5–7.5 and moderate general hardness (GH 3–15). This is a warm, soft-to-moderately-hard, near-neutral river fish, not a blackwater specialist and not a hard-alkaline lake species — its water chemistry should track a typical Southeast Asian lowland river rather than either extreme.
Feeding
Pangasius macronema is best treated as a nocturnal, opportunistic predator and scavenger — sources describe it as piscivorous, taking any fish or invertebrate it can swallow, alongside a broader omnivorous habit that includes bottom scavenging and some plant material. In the river it forages over open water and along the bottom, most actively after dark.
In the aquarium it accepts large meaty foods readily: whole fish, prawn, and large sinking pellets are all suitable. Because it is a genuine predator that will consume any tankmate small enough to fit in its mouth, feeding decisions and tankmate choices go hand in hand — anything housed with it must be too large to be eaten.
Mating
There is no documented account of natural courtship or pairing behaviour for Pangasius macronema in the wild or in captivity; like other Pangasiidae kept and farmed at scale, reproduction in this genus is achieved commercially through hormone induction rather than through observed natural mating displays. Data on wild spawning behaviour for this particular species is sparse.
Breeding
As with the other shark catfishes farmed across Southeast Asia, Pangasius macronema is bred commercially at scale using hormone-induced spawning — injecting ripe broodstock with pituitary extract or synthetic hormones to trigger egg release, followed by artificial fertilisation and pond or hatchery rearing. This is standard practice across Pangasiidae aquaculture and is not a home-aquarium technique.
It is essentially not bred in the home aquarium. The species grows too large for typical tanks to house a mature, conditioned breeding group, and it lacks the pair-bonding or nest-building behaviour that would make natural spawning practical in captivity. Anyone keeping this fish should do so purely for grow-out and observation, not with breeding in mind.
In the aquarium
Pangasius macronema is a genuine size-trap fish. It is sold small and cheap as an active, attractive schooling catfish, but it reaches at least 12 in and needs a correspondingly large footprint to swim and school naturally — sources recommend a minimum of roughly 210 US gal, and realistically it is a fish for a large public-style aquarium or pond rather than a typical home tank. Prospective keepers should confront the adult size before buying juveniles.
Its naked, scaleless skin makes it medication-sensitive: copper-based treatments and many standard medications should be dosed conservatively, often at half strength, as with loaches, puffers and other scaleless catfish. It also carries a stiff, locking dorsal spine typical of the family, which can snag in a net — move it in a container rather than netting it. It is a nocturnal, schooling fish that does best in a group with open swimming space, and because it is a capable predator, tankmates must be too large to be swallowed.
Conservation
The IUCN Red List assesses Pangasius macronema as Least Concern. It is a widespread species across the Mekong and Kapuas river systems and is not currently considered at risk at the species level.
As with other Mekong basin fishes, the longer-term outlook is tied to pressures on the river system itself — damming, altered flow regimes, sedimentation and fishing pressure across the Mekong and its tributaries — rather than any specific threat to this species. Data on population trends specific to Pangasius macronema is limited, and its Least Concern status reflects its broad distribution rather than detailed monitoring.