Taxonomy & naming
Pseudolais pleurotaenia was described by the French naturalist Henri Sauvage in 1878, originally placed in a different genus before later authors recognised it as distinct enough from Pangasius to warrant its own genus, Pseudolais — a small genus of Pangasiidae erected for species that share the family's shark-like build but differ in dentition and other anatomical details. The Catalog of Fishes treats Pseudolais pleurotaenia as the currently valid combination, and it remains the genus used on this page.
The family Pangasiidae, the shark catfishes, is a heavily revised group of Southeast Asian river catfishes that also includes the familiar Pangasius species sold in the aquarium and food-fish trades (the iridescent shark and its relatives). Pseudolais is one of the smaller genera within that family, alongside Pangasius and Helicophagus, and older literature or trade names may still list this species under a Pangasius-type combination; the genus Pseudolais is retained here as the accepted name.
Morphology
Pseudolais pleurotaenia has the classic pangasiid "shark catfish" profile: a streamlined, laterally compressed, silvery body, a forked tail, a tall triangular dorsal fin with a long filament, and a deeply notched adipose fin set well back near the tail — the combination that gives these catfish their freshwater-shark look. The mouth carries short barbels, in keeping with the genus name (pleurotaenia refers to a lateral stripe or band, and some populations show a faint dark lateral line or band along the flank).
Like all catfishes in this account, it is scaleless — its skin is naked rather than armoured or scaled, which has direct consequences for medicating it (see "In the aquarium"). Reported maximum size is about 15.5 in total length (14 in standard length), a large-bodied river fish rather than a small aquarium species, and growth in juveniles can be rapid once they are established and well fed.
Habitat
The species is native to large and medium-sized rivers of mainland Southeast Asia, recorded from the Mekong basin as well as the Chao Phraya, Meklong and Tapi basins, spanning parts of Thailand, Laos, Cambodia and Vietnam. Within these systems it uses both faster, rapid-flow river sections and slower, more sluggish stretches, moving between habitats rather than being tied to one current regime.
Water in these Southeast Asian lowland and mid-elevation rivers is warm and only mildly acidic to neutral; the species is reported from freshwater around 72–79 °F and pH 6.5–7.5. This is a warm, moving-water Asian river fish, not a soft, blackwater specialist — provide steady warmth and reasonably well-oxygenated conditions rather than assuming extreme soft-acid parameters.
Feeding
Pseudolais pleurotaenia is a nocturnal, benthic-leaning omnivore. In the wild it feeds mainly on aquatic insects and insect larvae, taking only minor amounts of plant material, and forages along the riverbed and through the water column mostly after dark rather than in open daylight.
In captivity it is not a fussy feeder and readily accepts sinking pellets, frozen foods and other prepared diets alongside any live or frozen invertebrate foods offered. Because it is a nocturnal forager by nature, feeding after lights-out — or at least ensuring food reaches the bottom — helps it compete for food rather than losing out to more visible, day-active tankmates.
Mating
There is no meaningful account of natural courtship or spawning behaviour for Pseudolais pleurotaenia in the aquarium literature, and that absence is itself informative: like the large Pangasius shark catfishes it resembles, this is a big river fish that reaches sexual maturity only at a size and age far beyond what a home aquarium provides. Where this species and its relatives are propagated at all, it is done commercially, typically using hormone-induced spawning of pond- or tank-held broodstock rather than natural pairing observed by hobbyists.
As a result there is no home-aquarium mating behaviour to describe. Keepers should not expect to see spawning behaviour, courtship colouration or pairing in a home tank; this is a species raised from wild or farmed stock, not bred in the hobby.
Breeding
Pseudolais pleurotaenia is not bred in home aquaria. Its biology follows the pattern of the other large Pangasiidae — the giant and iridescent shark catfishes farmed for food across Southeast Asia — where reproduction at commercial scale relies on hormone-induced spawning of mature broodstock held in ponds or hatchery tanks, not on natural pairing that a hobbyist could replicate. The fish simply grows too large, and matures too late, for any realistic home-tank breeding project.
Any fish available in the trade should be assumed wild-caught or farmed as a food/pond fish rather than hobby-bred. There is no parental care to speak of in captivity, since the species is not maintained through its full reproductive cycle by aquarists; treat this account's breeding facts as reflecting commercial hormone-induced propagation, not a home-achievable spawn.
In the aquarium
This is a species best approached with the size trap firmly in mind: small, inexpensive, silvery juveniles are sometimes sold without any indication that the adult fish reaches around 15.5 in total length, a size that outgrows the great majority of home aquariums. Anyone considering this species should plan for a very large, long system from the outset — public-aquarium or pond-scale housing is realistic for an adult, a standard home tank is not — or avoid buying it as a small juvenile in the first place.
Because it is scaleless like other naked-skinned catfish, it is medication-sensitive: copper-based treatments and many standard medications should be dosed conservatively, often at reduced strength, exactly as with loaches, puffers and other scaleless fishes. It is also a nocturnal fish that appreciates cover and dim conditions during the day, becoming more active after dark. Handle it with care rather than a net where possible, since pangasiid catfishes carry stiff fin rays that can catch in netting; a soft container is gentler and safer for both fish and keeper. Given its size, activity level and food-fish/farmed background, it is far better suited to very large public or research systems than to the home hobby.
Conservation
The IUCN Red List assesses Pseudolais pleurotaenia as Least Concern. It is a freshwater species with a fairly broad distribution across several major Southeast Asian river basins — the Mekong, Chao Phraya, Meklong and Tapi — which supports its non-threatened status at the present time.
That range-wide picture does not remove the pressures acting on Mekong and Chao Phraya basin fishes generally: damming and altered flow regimes, sedimentation, and heavy regional fishing pressure affect many species sharing these rivers. As with other Pangasiidae, much of the trade and food-fish supply for this group relies on wild-caught or pond-farmed stock rather than aquarium-hobby breeding, so its conservation story is tied to broader river-basin health rather than to aquarium demand.