Taxonomy & naming
Ompok argestes was formally described by Kalana Sudasinghe and Madhava Meegaskumbura in 2016 (Zootaxa 4158), part of a wave of taxonomic work that has clarified Sri Lanka's long-confused silurid catfishes. It sits in the family Siluridae — the Old World sheatfishes and glass catfishes — within the genus Ompok, a group of South and Southeast Asian river catfishes that also includes far larger species. The Catalog of Fishes (Eschmeyer, CAS) treats Ompok argestes as the valid name for this species.
The specific epithet argestes refers to argestes, the classical Greek name for a west-southwest wind, an allusion to the species' distribution in the southwestern wet zone of Sri Lanka. Before this description, Sri Lankan Ompok populations had at times been lumped with other regional silurids; the 2016 paper separated out a genuinely endemic, range-restricted species based on fin-ray counts, vertebral counts and body proportions.
Morphology
This is a small, laterally compressed silurid with the classic "glass/butter catfish" silhouette: an elongated, knife-like body, a long-based anal fin, and a short, low dorsal fin set well forward. FishBase records four dorsal soft rays, 56–63 anal soft rays and 48–52 vertebrae — meristic detail that helps separate it from close relatives. The maxillary barbels are long, reaching to or just past the base of the dorsal fin, and the predorsal profile is evenly convex rather than sharply humped.
Body colouration is a mottled, semi-translucent pattern typical of the group, giving rise to the trade name "glass catfish" alongside "wetzone butter catfish." Maximum recorded length is 6 in SL (FishBase) — modest for the genus Ompok, whose larger species are pond- and public-aquarium fish, but this species should still be regarded as an adult-sized river fish in its own right, not a permanently tiny nano species. As in every silurid, the skin carries no scales, which makes the fish more sensitive to copper and many medications than a scaled tankmate.
Habitat
Ompok argestes is endemic to the lowland wet zone of southwestern Sri Lanka, where it has been collected from slow-flowing, shaded streams and small rivers with submerged root tangles and overhanging marginal vegetation. The substrate at known sites is typically soft — mud or accumulated leaf litter — consistent with a fish that shelters among cover rather than holding in open current.
It is described as an uncommon, range-restricted species, and its entire known distribution lies within a relatively small area of Sri Lanka's wet zone, a region under sustained pressure from land conversion and freshwater habitat modification. No published temperature or pH range was located for this species specifically; hobbyist care should follow the general profile of shaded Sri Lankan wet-zone streams — warm, soft, tannin-influenced water — until better data exists, and keepers should not assume this species tolerates the harder, more alkaline water that characterises unrelated catfish groups.
Feeding
No species-specific dietary study was found in the cached sources. Based on its body plan, barbel length and closely related silurids, Ompok argestes is presumed to be a nocturnal or crepuscular predator of small aquatic invertebrates and possibly small fish, foraging by scent and touch along the shaded, root-tangled margins where it has been collected. Data on natural diet is sparse and should not be over-stated.
In the aquarium, silurids of this build generally accept sinking pellets, frozen bloodworm, and other meaty foods once settled, though — given the lack of confirmed husbandry data for this exact species — any feeding regime for Ompok argestes should be treated as inferred from its relatives rather than established fact.
Mating
Nothing specific to Ompok argestes' courtship or spawning behaviour was found in the cached sources — unsurprising for a species only described in 2016 and evidently uncommon even within its native range. Among the Siluridae as a whole, small to medium species have not been reliably bred in home aquaria, and the larger genus members (Wallago, larger Ompok, Silurus) are predominantly river spawners whose captive reproduction, where it happens at all, is farm- or hormone-induced rather than a natural pair-bond in a tank.
Breeding
There is no documented aquarium-breeding record for Ompok argestes in the cached sources, and none is claimed here. As with glass and sheatfish catfishes generally, home breeding of this genus is not an established practice: true glass catfish (Kryptopterus) are essentially never bred in captivity and the trade in them is wild-caught, while the larger river-dwelling Ompok and Wallago species that are propagated at all are produced on farms using hormone induction, not spontaneous tank spawning. Given this species' small, fragile, endemic wild population, any aquarium stock should be assumed wild- or farm-collected rather than captive-bred, and keepers should not expect to reproduce it at home.
In the aquarium
Ompok argestes reaches about 6 in — a real adult size that calls for a properly sized tank with swimming room, not a bowl-sized nano setup, even though it is far smaller than the genus's giant relatives. Being scaleless, like all silurids it is medication-sensitive: dose copper-based treatments and many standard medications conservatively, following the reduced-dose practice used for loaches, puffers and eels. Silurid catfishes also carry stiff pectoral and dorsal spines that can lock and snag in netting, so this species is best moved in a container rather than chased with a net.
Given its shaded, root-tangled, soft-substrate native streams, aquascape with dense cover — driftwood, root tangles and overhanging plants — and keep lighting subdued, since the species is presumed crepuscular to nocturnal like its relatives. Because it comes from an uncommon, range-restricted wild population and has no established captive-breeding pathway, prospective keepers should treat any specimen in the trade as coming from limited wild or farmed stock and should not expect the species to be self-sustaining in the hobby.
Conservation
The IUCN Red List assesses Ompok argestes as Vulnerable. As a narrow-range endemic confined to lowland wet-zone streams in southwestern Sri Lanka, it is exposed to the same habitat-loss pressures — deforestation, agricultural conversion, water pollution and stream modification — that threaten many of the island's other endemic freshwater fishes.
Because the species was described only in 2016 and appears uncommon even within its restricted range, its population trend and any aquarium trade impact are not well documented in the sources reviewed here. Its conservation status underscores that this is not a fish to collect casually from the wild; any interest in keeping it should be paired with awareness of its fragile, geographically tiny distribution.