Taxonomy & naming
Ompok hypophthalmus was described by the Dutch ichthyologist Pieter Bleeker in 1846. It sits in the family Siluridae — the Old World sheatfishes and glass catfishes, which also contains Kryptopterus, Wallago and the European Silurus — and in the genus Ompok, a group of roughly two dozen species spread across South and Southeast Asia.
The species has a genuinely messy taxonomic history. A 2003 revision by Heok Hee Ng clarified that what had long been called "Ompok hypophthalmus" across Sumatra, the Malay Peninsula and parts of Borneo was in fact a group of superficially similar but distinct species; the true O. hypophthalmus, in the strict sense used by the Catalog of Fishes, is now restricted to Java and the Barito River drainage of southern Borneo. Older literature, museum labels and even some aquarium-trade references may therefore apply the name too broadly, and specimens from outside that core range should be treated with caution.
Morphology
Like other Siluridae, Ompok hypophthalmus has an elongated, laterally compressed body, a long-based anal fin running most of the length of the underside, a small or absent adipose fin, and a short dorsal fin set well forward. The mouth carries barbels used to feel out prey and food in low light or murky floodwater. The skin is completely scaleless, as in all silurid catfishes.
FishBase records a maximum size of 12 in standard length for the species — a substantial fish, not the small glass-catfish-style animal the family name might suggest. Ng's 2003 study of wild-caught floodplain specimens found a size range of roughly 3–12 in total length, with females maturing around 4.5 in TL and males somewhat later, around 8.5 in TL, indicating a fish that keeps growing well past first maturity.
Habitat
Ompok hypophthalmus is a tropical Asian freshwater species. Its confirmed range covers Java and the Barito River drainage of southern Borneo, with the wider O. hypophthalmus species-group historically reported (under the same name, before the 2003 revision) across the lower Mekong and central Thailand as well. It is a demersal, bottom-oriented fish of rivers and their associated floodplains.
The species moves into seasonally flooded habitat during high water, sheltering and foraging around submerged woody vegetation and flooded forest margins — the classic floodplain lifestyle shared by many Southeast Asian river fishes. Water data specific to this species is sparse; it should be kept as a warm, soft-to-neutral tropical Asian river fish, matching the seasonal floodplain rivers it inhabits, rather than assigned a generic blackwater profile without direct evidence.
Feeding
Ompok hypophthalmus is built like a typical silurid predator — a nocturnal hunter that takes fish and invertebrates it can overpower and swallow whole. Its barbels and forward-set eyes suit foraging after dark and in the turbid water of a flooded plain, where visual hunting alone would fail.
In the aquarium it should be treated as a piscivore: it will take frozen and live fish, prawn, and large meaty foods, and it will not distinguish between offered food and tankmates it is able to swallow. Any companion fish need to be robust species too large for it to eat.
Mating
This species is a floodplain spawner: a 2017 Indonesian study on the Kampar Kiri River (Sumatra) documenting the reproduction of the wider Ompok hypophthalmus group tied spawning activity to seasonal hydromorphological changes — reproduction is cued by the rise and fall of floodwater rather than fixed pairing behaviour or a nest. There is no evidence of parental care or of a distinct courtship display; like many river and floodplain catfishes, breeding is a mass, season-triggered event rather than an individual pairing.
As with most larger Siluridae, courtship and spawning have not been documented or replicated in the aquarium, and captive broodstock are not known to be conditioned or spawned by hobbyists.
Breeding
Home breeding of Ompok hypophthalmus is not established. Its glass-catfish relatives (Kryptopterus) are essentially never bred in captivity and the trade in them is entirely wild-caught; the larger sheatfish genera in this family — Ompok, Wallago, Silurus — are river spawners tied to seasonal flood cues, and where they are propagated at all it is on a farmed or hormone-induced commercial basis rather than in home aquaria.
Nothing in the available literature suggests aquarists have replicated a spawn of this species. Prospective keepers should treat it as a wild-collected floodplain fish with no realistic captive-breeding pathway, and should be honest that the specimens in the trade — where available at all — are taken from the wild.
In the aquarium
Ompok hypophthalmus is a size-trap fish: it is sometimes sold small, but FishBase records it reaching 12 in SL, a genuinely large catfish that outgrows the great majority of home aquaria. Anyone considering it needs to plan for an adult fish that size from the outset, in a large, long tank with robust filtration — not a fish to buy on the strength of its juvenile size.
Because it is completely scaleless, it is medication-sensitive in the same way as loaches, puffers and eels — copper-based treatments and many standard medications should be dosed conservatively, often at half strength. It is a nocturnal predator that appreciates cover such as driftwood, overhangs or dense planting to retreat into during the day, becoming active after dark. As with most silurid catfishes it lacks the heavily locking spines of some other catfish families, but it should still be handled gently and moved in a container rather than a net where practical. Tankmates must be too large for it to swallow; smaller fish will eventually disappear.
Conservation
Ompok hypophthalmus has not been evaluated by the IUCN Red List (NE). Its confirmed range — Java and the Barito River drainage of Borneo — places it in a region under heavy pressure from floodplain drainage, deforestation, and river modification, all of which affect the seasonally flooded habitat this species depends on for both feeding and reproduction.
Because the wider species group was only clarified taxonomically in 2003, population data specific to the true O. hypophthalmus is limited, and much of what is recorded in fisheries literature for "Ompok hypophthalmus" from outside its confirmed range likely refers to related, now-separated species. A formal assessment would need to account for this taxonomic history.