Taxonomy & naming
Pseudolais micronemus was first described by the Dutch ichthyologist Pieter Bleeker in 1846. Like much of Siluriformes, it has carried several generic combinations in the older literature before settling in Pseudolais, and older texts or trade lists may still place it under names once used loosely for Pangasiidae genera; the Catalog of Fishes (Eschmeyer, California Academy of Sciences) is treated here as the authority for the valid combination, Pseudolais micronemus.
The genus Pseudolais sits within Pangasiidae, the Asian shark catfishes, alongside the better-known Pangasius and Pangasianodon. The family name reflects the superficially shark-like silhouette shared by these fast-swimming, open-water river catfishes — a forked tail, streamlined body and prominent dorsal fin — rather than any close relationship to true sharks.
Morphology
This is a large, torpedo-shaped catfish built for life in open river channels: a compressed, elongated body, a tall triangular dorsal fin, a deeply forked caudal fin, and an adipose fin set well back near the tail. Like other Pangasiidae it carries barbels used to feel out food and surroundings in turbid river water — the epithet micronemus ("small filament/thread") alludes to its comparatively short barbels next to other shark catfishes.
Maximum recorded length is around 39.5 in, a genuinely large adult size that many keepers underestimate when they buy juveniles at a few centimetres. As in other catfishes the skin is scaleless (naked), which makes the species more sensitive than scaled fish to copper-based medications and some other treatments — a consideration for anyone keeping juveniles in a community setting before they are moved on. The fish also carries stiff, serrated fin spines typical of the order; adults are powerful enough that any handling should use a container rather than a net.
Habitat
Pseudolais micronemus is benthopelagic — moving through the water column as well as near the bottom — and potamodromous, undertaking migrations entirely within fresh water rather than to the sea. It inhabits large and medium-sized rivers, most notably the Mekong basin and the Hue River system, and its range extends across parts of the Malay Peninsula and the islands of Sumatra, Java and Borneo.
As a river-channel species it lives in flowing, well-oxygenated water rather than still or heavily vegetated habitat, moving with the seasonal rise and fall of its river systems. Detailed published temperature and pH ranges for the species specifically are sparse; as a lowland Southeast Asian river fish it is reasonably assumed to prefer warm, soft-to-moderately hard, neutral-to-slightly-acidic water typical of Mekong and Sundaic drainages, though keepers should treat this as a general guide rather than a precise figure.
Feeding
Pseudolais micronemus is omnivorous, taking both animal and plant matter along with detritus as it forages through its river habitat — a generalist diet typical of large Pangasiidae rather than a specialised predator or herbivore.
Juveniles occasionally seen in the trade will take sinking pellets, frozen foods and most prepared aquarium foods readily, foraging actively rather than exclusively after dark. Because the species is not realistically kept to adulthood in home aquaria, feeding guidance in practice applies only to the juvenile stage; growth is rapid on a varied diet, which is itself part of why the species quickly outgrows hobby tanks.
Mating
Wild reproduction in Pangasiidae follows the seasonal, migratory pattern typical of large Southeast Asian river catfishes: adults move upriver in response to rising water levels associated with the monsoon and spawn in open channels, releasing large numbers of pelagic eggs and sperm into the current rather than pairing off or guarding a nest site. Specific published detail on the mating behaviour of Pseudolais micronemus itself is sparse, but the pattern in commercially important relatives such as Pangasius and Pangasianodon is well documented and is the best available guide for the genus.
In practice, commercial production sidesteps natural courtship almost entirely: broodstock are held in ponds and mating is replaced by hormone-induced stripping and artificial fertilisation, described further below.
Breeding
Pseudolais micronemus is a large, commercially significant shark catfish, and like its Pangasiidae relatives it is farm- or hormone-bred at scale rather than bred in the home aquarium. Producers hold broodstock to maturity and induce spawning with hormone preparations — historically pituitary gland extract (PG) and more recently synthetic analogues such as LHRH-A — after which eggs are stripped, fertilised and hatched under controlled hatchery conditions.
This is essentially the only way the species reproduces in captivity. It grows too large, and requires conditions and broodstock management too specialised, for spontaneous spawning in a home tank; hobbyists should not expect to breed this species, and any aquarium specimens available in the trade originate from commercial hatchery production or wild collection, not from aquarist-bred stock.
In the aquarium
Pseudolais micronemus is a poor long-term aquarium prospect and a textbook case of the size trap: it is sold small and grows to around 39.5 in, far beyond what any home aquarium can accommodate. Anyone offered a juvenile shark catfish under this or a related name should plan for an adult that needs a pond-sized system or should decline the purchase altogether — there is no responsible way to keep this species to full size in a typical home tank.
For the juvenile stage sometimes seen in the trade, standard river-catfish care applies: strong filtration and current, high dissolved oxygen, and open swimming space, since this is an active schooling river fish rather than a sedentary bottom-dweller. Its skin is scaleless, so treat medications (especially copper-based products) conservatively, as with loaches, puffers and other naked-skinned catfish. It also carries locking, serrated fin spines that can snag a net and jab the handler, so move it in a container rather than netting it. Given the near-certainty of outgrowing home aquaria, this species is best regarded as a food/aquaculture fish that occasionally and inadvisedly enters the ornamental trade, not as a genuine long-term aquarium subject.
Conservation
The IUCN Red List assesses Pseudolais micronemus as Least Concern, reflecting its wide distribution across the Mekong basin, the Hue River, the Malay Peninsula and the islands of Sumatra, Java and Borneo, and the absence of evidence for a range-wide population decline.
As with other large Mekong and Sundaic river fishes, the species' habitat is nonetheless exposed to pressures common across the region — damming and altered river hydrology, sedimentation, and heavy fishing pressure on migratory river fish stocks — even where the species itself is not currently classified as threatened. Much of its presence in trade, whether as food or as an occasional ornamental juvenile, is tied to wild river fisheries and pond aquaculture rather than to any conservation-driven breeding program.