Taxonomy & naming
Ompok sabanus was described by the American herpetologist-ichthyologist Robert F. Inger and the Malaysian naturalist Phui Kong Chin in 1959, with material from Borneo giving rise to the epithet sabanus, after Sabah, the Malaysian state on Borneo's northern tip. It sits in the family Siluridae, the sheatfishes, alongside the true glass catfishes (Kryptopterus), the Asian butter catfishes (Ompok), the giant Wallago, and the European and Asian Silurus.
Siluridae nomenclature has been reshuffled repeatedly, and older literature and aquarium labels sometimes lump this and related species under Ompok or the historic genus name Cryptopterus (an alternate spelling still seen on some aquarium-trade invoices and forum threads). The Catalog of Fishes maintains Ompok sabanus as the valid combination, and that is the name used here; it is not synonymised with the smaller, far more common glass catfishes K. vitreolus or K. bicirrhis, which are separate species within the same genus.
This fish was long listed as Kryptopterus sabanus; Eschmeyer's Catalog of Fishes places the species in Ompok, and the current combination Ompok sabanus is followed here.
Morphology
The genus name Kryptopterus comes from the Greek kryptos, "hidden", and pteron, "wing" or "fin", a reference to the vestigial, all-but-invisible dorsal fin that gives the genus its glass-catfish silhouette: a long, laterally compressed body tapering to a deeply forked tail, an elongated anal fin running most of the body's length (55–66 soft rays), and a single pair of long maxillary barbels trailing from the upper jaw. Like other glass catfishes it is scaleless, and the body wall is thin and largely transparent, letting the vertebral column and swim bladder show through as a pale, silvery-outlined thread.
Ompok sabanus reaches a maximum recorded size of about 5.9 in standard length, distinctly larger than the popular dwarf glass catfish K. vitreolus (around 2.4–2.8 in) that is far more commonly seen in the aquarium trade. That size difference matters: juveniles of the larger glass catfish species are not always reliably told apart from small vitreolus at point of sale, and a fish sold as a "glass catfish" at 1.6 in can be this species heading toward more than double that length.
Habitat
Ompok sabanus is native to Borneo, with records concentrated in the island's northeastern and western river systems — the political territories of Sabah and Sarawak (Malaysia) and Kalimantan (Indonesia) drain these same catchments. It occupies flowing lowland and hill-stream rivers, holding in loose shoals in open water rather than hugging cover, a habit shared with other Siluridae glass catfishes.
Water in these Bornean rivers is warm tropical freshwater, with FishBase recording a preferred range of roughly 73–81 °F. As with most Southeast Asian blackwater- and clearwater-river fishes, the species is best kept in soft, slightly acidic to neutral water; the source material available does not give a documented pH range specific to this species, so aquarists should default to the general soft, gently acidic conditions typical of its Bornean river habitat rather than assuming hard or alkaline water.
Feeding
Glass catfishes are midwater micro-predators. In the wild, Ompok sabanus almost certainly forages on small aquatic invertebrates and drifting insect material picked from the water column, in keeping with the feeding style documented for its close relatives in the genus.
In the aquarium it needs small live or frozen foods — bloodworm, daphnia, brine shrimp, and other small crustaceans — to settle in and feed confidently; once established it can be brought onto good-quality fine dry foods, but a mix that includes regular live or frozen offerings keeps a shoal in the best condition. It is a shy, unhurried feeder that is easily out-competed by bold or fast-moving tankmates, so food should be offered where the shoal is holding station rather than dropped at the surface for boisterous fish to intercept first.
Mating
No courtship or spawning behaviour has been documented for Ompok sabanus in the wild or in captivity. Among the glass catfishes generally, what little is known points to open-water egg scattering during seasonal high-water periods, likely tied to rainy-season flooding, but this pattern has not been confirmed specifically for O. sabanus and should not be taken as established fact for the species.
Breeding
Ompok sabanus is, for practical purposes, not bred in the home aquarium. Every specimen reaching the trade is wild-caught from Borneo, and this holds true across the glass catfish group as a whole: even the much more widely kept dwarf glass catfish has no reliable, repeatable hobbyist spawning method, and the handful of documented captive breedings of related Kryptopterus species have relied on hormone induction under controlled research or commercial-farming conditions rather than natural spawning behaviour in a home tank.
Aquarists should not expect this species to breed under normal aquarium conditions, and should be honest with themselves that keeping a shoal healthy and long-lived — not breeding it — is the realistic goal.
In the aquarium
Ompok sabanus needs to be sized correctly from the start: at up to 5.9 in SL it is meaningfully larger than the diminutive glass catfish species most beginners picture, and a shoal of adults needs a long, spacious tank with plenty of open swimming water, not the small community setups often recommended for glass catfish in general. It should always be kept in a shoal of at least six, ideally more — a lone or thinly-numbered glass catfish is a stressed, short-lived one, and dense grouping is part of how the species feels secure enough to feed and colour up.
Being scaleless, it is medication-sensitive in the same way as loaches, other naked-skinned catfishes, and eels: copper-based treatments and many standard medications should be dosed conservatively, often at reduced strength, and the fish should be watched closely during any treatment. Its transparency also makes it a poor barometer of subtle health problems that would show as colour change in an opaque fish, so water quality and gentle, well-oxygenated flow matter more than usual. It is peaceful and non-aggressive, does best with calm, similarly unhurried tankmates, and — like other Siluridae — lacks the heavy locking spines of many armoured catfish families, so it can be netted with the ordinary care due any thin-bodied, easily stressed fish.
Conservation
The IUCN Red List assesses Ompok sabanus as Least Concern, reflecting its relatively wide distribution across multiple river systems in northeastern and western Borneo and a low estimated vulnerability to fishing pressure. It is not currently considered at risk at the species level.
That said, its entire range sits within Borneo's river catchments, an island under sustained pressure from logging, oil-palm conversion, and mining-related sedimentation, all of which degrade the clear, flowing water this species and its Siluridae relatives depend on. Because the aquarium trade relies entirely on wild collection rather than captive breeding, the long-term health of its native rivers — not just the formal Red List category — is what will determine whether it stays available and abundant.