Taxonomy & naming
Ompok borneensis was described by the Austrian ichthyologist Franz Steindachner in 1901 from the Baram River, Sarawak state, on the island of Borneo in eastern Malaysia. The holotype is held at the Academy of Natural Sciences of Philadelphia (ANSP 114890). It belongs to the family Siluridae — the true sheatfishes and glass catfishes of Europe, Africa and Asia — and to the genus Ompok, a group of small-to-medium Southeast Asian river sheatfish that sit alongside the more famous glass catfish genus Kryptopterus and the giant Wallago.
Ompok jaynei, described by Fowler in 1905, is a junior synonym of O. borneensis, as recognised by Ng & Tan (2004) and Kottelat (2013). The Catalog of Fishes (Eschmeyer, CAS) treats Ompok borneensis as the valid name and lists the species as Not Evaluated in its own right for conservation status separate from the IUCN Red List entry discussed below. The species epithet borneensis simply marks its type locality: the island of Borneo.
Morphology
Like other Ompok, O. borneensis has the classic sheatfish silhouette: a long, laterally compressed, scaleless body, a long-based anal fin, a small or absent adipose fin, and a short dorsal fin set well forward. The skin is naked rather than scaled or bony-plated, the hallmark of the Siluridae, which makes the species — like loaches, puffers and true eels — more sensitive to copper and many medications than scaled fish.
Non-type specimens examined from Sarawak (near Sibu, Borneo) measured roughly 3–4.5 in standard length, putting typical adult size at about 3–4.5 in SL. No verified maximum length beyond this range has been published for the holotype description. Colouration in Ompok generally runs silvery to olive-grey along the flanks with a pale belly, though detailed colour-pattern description specific to O. borneensis is not available from the sources consulted here.
Habitat
Ompok borneensis is known from the Baram River basin in northern Borneo (Sarawak, Malaysia), a freshwater river system draining into the South China Sea. As with most Ompok, it is a lowland to mid-elevation river fish rather than a still-water or blackwater specialist.
Detailed physicochemical data specific to O. borneensis has not been recorded in the cache; closely related Ompok bimaculatus is documented from quiet, shallow (roughly 2–5 ft) muddy streams and rivers at pH 6.0–8.0, hardness 4–28 dH and tropical temperatures of 68–79 °F, and this gives a reasonable proxy for the genus's general habitat preferences pending species-specific data.
Feeding
Specific dietary data for Ompok borneensis has not been documented in the sources consulted. The related O. bimaculatus is omnivorous, taking both plant matter and small fish or invertebrates in the wild, and Ompok generally forage opportunistically along the riverbed and in the water column, often most active around dusk.
In the aquarium, where Ompok are occasionally available through the trade, they are usually fed a mixed diet of sinking pellets, frozen bloodworm and brine shrimp, and other meaty foods; tankmates should not be small enough to be swallowed by an adult fish of this genus.
Mating
No courtship or spawning behaviour has been documented for Ompok borneensis specifically. Among Siluridae, the well-studied glass catfishes (Kryptopterus) are essentially not bred in captivity and the aquarium trade in them remains wild-caught, while larger river sheatfish such as Wallago and Silurus are river spawners whose reproduction in the wild is tied to seasonal flooding and flow cues rather than fixed pairing or nest behaviour. Ompok borneensis, as a lesser-known river-dwelling member of the same family, most plausibly follows a similar river-spawning pattern, but this has not been confirmed by direct observation.
Breeding
Home aquarium breeding of Ompok borneensis is not established. Related, larger Ompok and Siluridae more broadly are propagated commercially in Southeast Asian aquaculture via hormone-induced spawning at hatchery scale rather than through natural courtship in captivity — the same pattern documented for O. bimaculatus. There is no record of parental care in this genus; eggs are not guarded.
Hobbyists should not expect to breed this species at home. Any specimens seen in the aquarium trade are very likely wild-collected from the Baram River system rather than captive-bred, which is worth bearing in mind for the species' conservation footprint.
In the aquarium
Ompok borneensis is rarely, if ever, seen in the aquarium trade, and detailed husbandry data specific to the species is sparse. Adult size of roughly 3–4.5 in SL is modest for a sheatfish, but as with all Ompok the fish is scaleless, so any medication — especially copper-based treatments — should be dosed conservatively, at half strength or less, the same precaution used for loaches, puffers and eels.
Siluridae in general carry a stiff dorsal spine and are best netted with care or moved in a container to avoid tangling; they are largely nocturnal river fish that appreciate cover during the day and open swimming space at night. Given the lack of established husbandry data and the near-total absence of captive breeding, keepers considering this species should treat it as a specialist, likely wild-collected river fish rather than a routine community catfish, and should verify sourcing before purchase.
Conservation
The IUCN Red List has assessed Ompok borneensis as Near Threatened. The species' known range is restricted to the Baram River basin of northern Borneo, a system facing pressure from logging, oil-palm agriculture and associated sedimentation across much of Sarawak.
Because the species is not established in captive breeding, any aquarium presence relies on wild collection from the Baram system, which argues for caution about collection pressure given the Near Threatened rating. Data on population trends specific to O. borneensis is sparse.