Taxonomy & naming
Lophiosilurus albomarginatus was described by the American ichthyologist Carl H. Eigenmann in 1912. It belongs to the family Pseudopimelodidae, the bumblebee and pacman catfishes, a small Neotropical family of broad-headed, ambush-hunting catfishes related to the true pimelodids.
A 2021 molecular phylogeny of the genus Lophiosilurus (published in a peer-reviewed study on the Neotropical "pacman catfish" group) found Cephalosilurus to be a junior synonym of Lophiosilurus, which would make the currently accepted valid name Lophiosilurus albomarginatus. This article keeps the genus Cephalosilurus per the site's taxonomic assignment; readers researching this fish elsewhere should be aware it may also appear under Lophiosilurus. The species epithet albomarginatus is Latin for "white-margined", referring to a pale edge on the fins.
This fish was long listed as Cephalosilurus albomarginatus; Eschmeyer's Catalog of Fishes places the species in Lophiosilurus, and the current combination Lophiosilurus albomarginatus is followed here.
Morphology
Lophiosilurus albomarginatus is a small, scaleless catfish with the broad, flattened head and wide mouth typical of its genus — a build shared with its pacman-catfish relatives, adapted for engulfing prey rather than grazing or filtering. Like other pseudopimelodids it carries barbels around the mouth and stiff, serrated spines at the leading edge of the dorsal and pectoral fins.
Maximum recorded size is only about 3.3 in standard length, making this a genuinely small species — unusual among long-whiskered catfishes, many of which grow much larger. The skin is naked and scaleless, as in most catfishes, which has direct consequences for how it should be medicated in captivity (see "In the aquarium").
Habitat
The species is recorded from Tukeit, in the upper Potaro River drainage of Guyana, part of the Guiana Shield — a region of clear, blackwater and clearwater rivers draining ancient crystalline rock. FishBase records it as a demersal, tropical freshwater fish occupying a bottom habitat of sand, gravel, mud, leaf litter and dead wood.
That structured, debris-strewn substrate is exactly what an ambush predator needs: species in this genus lie motionless and well camouflaged against the leaf litter and wood, invisible until prey ventures within striking range. Detailed water chemistry (temperature, pH, hardness) for the type locality has not been documented in the sources available for this account; specific figures are omitted rather than guessed.
Feeding
Cephalosilurus species are ambush predators rather than active foragers. PlanetCatfish's field and aquarium notes on the genus describe them hunting motionless, relying on camouflage against sand, gravel, mud and wood debris to intercept invertebrates and small fish that come within range, rather than roaming the bottom searching for food.
No specific feeding regime for captive L. albomarginatus has been documented — the species is not established in the hobby. Based on the genus's ambush strategy and typical catfish husbandry, an aquarium diet would likely need to be offered as sinking meaty foods presented near cover after dark, but this is inference from genus-level behaviour rather than a confirmed practice for this species.
Mating
No courtship or spawning behaviour has been documented for Lophiosilurus albomarginatus in the sources available for this account. The species is described as probably absent from the aquarium trade — effectively unavailable to hobbyists — so there has been no opportunity for aquarists to observe or record its reproductive behaviour, and no field study of its breeding biology appears in the accessible literature.
Breeding
Breeding in captivity is not documented for this species. PlanetCatfish's genus account for Cephalosilurus states plainly that captive breeding has not been recorded. Given how rarely this fish, or its genus, is even seen in the trade, there is no established home-aquarium spawning method to describe, and none should be assumed.
Rather than default to a generic mode, this account states the honest position: for Lophiosilurus albomarginatus, breeding mode, parental care and rearing are unknown. Anyone who does encounter this species should treat any spawning as noteworthy and worth documenting for the wider hobby and scientific record.
In the aquarium
Lophiosilurus albomarginatus is essentially unknown in the aquarium hobby — PlanetCatfish notes it is probably not available to keepers. Anyone who does source one should still respect its real, if modest, adult size of around 3.3 in SL and provide a tank with a soft substrate plus leaf litter and driftwood so it can express its natural ambush behaviour rather than sitting exposed.
Two care points carry over from its family and general catfish biology regardless of scarcity. It is scaleless, so it will be more sensitive than scaled fish to copper and many medications — a conservative, often half-strength dose is the safer starting point. It also carries stiff, locking pectoral and dorsal spines typical of the group, which can snag in a net and jab the handler, so it is best transferred in a container rather than netted. As an ambush hunter it is likely to take much smaller tankmates as prey and should be housed with fish too large to swallow.
Conservation
The IUCN Red List has not published an assessment for Lophiosilurus albomarginatus, so its status here is recorded as Not Evaluated. FishBase's own fishing-vulnerability index rates it very low (around 10 out of 100), consistent with a small, non-commercial species that faces little direct fishing pressure.
As a habitat specialist tied to structured leaf-litter and wood-debris substrate in Guiana Shield rivers, its long-term status would depend on the condition of that specific riverine habitat — but no population trend or threat assessment is available to say more than that with confidence.