Taxonomy & naming
Pseudobunocephalus iheringii was described by the Belgian-British ichthyologist George Albert Boulenger in 1891 as Bunocephalus iheringii. It remained in Bunocephalus, the original banjo catfish genus, for well over a century before the American ichthyologist John P. Friel split the family in 2008 and erected Pseudobunocephalus to hold this species and its close relatives, which differ from true Bunocephalus in details of skeletal and body-shape anatomy. The species belongs to the family Aspredinidae, the banjo catfishes, within the order Siluriformes.
The genus name Pseudobunocephalus combines the Greek pseudo- ("false") with Bunocephalus, signalling its close but separate relationship to that genus. Older literature and some hobby sources still refer to this fish under its original combination, Bunocephalus iheringii; the Catalog of Fishes treats Pseudobunocephalus iheringii as the currently valid name.
Morphology
Like all banjo catfishes, Pseudobunocephalus iheringii has the family's unmistakable shape: a broad, flattened, disc-like head and forebody tapering abruptly into a slender, whip-like tail, which gives the fish its "banjo" silhouette. The skin is entirely scaleless and covered in small tubercles and fleshy fringes that help it disappear against sand, dead leaves and detritus. Colouration is a mottled sandy brown to grey, an effective camouflage pattern for a fish that spends most of its time partly buried.
Males reach roughly 2.5 in total length, and the species as a whole stays under about 3 in standard length, making it one of the smaller aspredinids kept in the hobby. It carries pectoral and dorsal spines typical of catfishes generally, though these are not confirmed to be venomous in this species. As with other scaleless catfishes, the naked skin makes it noticeably more sensitive to copper-based and other harsh medications than scaled fish.
Habitat
Pseudobunocephalus iheringii is native to southern South America, recorded from the La Plata River basin and the Laguna dos Patos system spanning southern Brazil and Paraguay. It is a freshwater species with no tolerance noted for brackish conditions.
It lives in small rivers and streams shaded by marginal vegetation, where it shelters among aquatic plants and accumulations of detritus such as dead leaves and branch remains. This detritus-rich, shaded habitat suits its camouflage and its nocturnal, bottom-hugging lifestyle, and it is rarely seen in open water during the day.
Feeding
This is a nocturnal benthic omnivore and micro-predator. In the wild it forages over the riverbed after dark, taking small invertebrates and detritus, its flattened body and cryptic pattern letting it approach prey unnoticed while remaining hidden from its own predators by day.
In the aquarium it accepts sinking pellets and a range of frozen foods — bloodworm, blackworm, daphnia and brine shrimp are all reported to be taken readily. Because it feeds mainly at night, food is best offered after the lights go out so this shy forager is not out-competed by more active tankmates.
Mating
Courtship and spawning behaviour for Pseudobunocephalus iheringii have not been documented in accessible sources, and breeding of this species in the aquarium is very rare. What is known comes largely from the biology of the wider family Aspredinidae: in several banjo catfish genera the female carries the fertilised eggs attached externally to the skin of her belly, held in place by short fleshy stalks called cotylephores, until they hatch.
Whether Pseudobunocephalus iheringii follows this egg-carrying strategy specifically has not been confirmed in the sources available for this account, and it should not be assumed without direct evidence. Data on this species' reproductive behaviour is genuinely sparse.
Breeding
Breeding of Pseudobunocephalus iheringii in captivity is essentially undocumented. No aquarium spawning reports were found, and given how poorly the family's smaller, obscure species are studied, that is unsurprising rather than unusual — most banjo catfishes outside a handful of well-known genera are simply never bred at home.
Aquarists should not expect to breed this species and should treat any wild-caught or imported stock as effectively unreplaceable through home breeding; the honest position, based on available evidence, is that its reproductive biology and any triggers for captive spawning remain unknown.
In the aquarium
Pseudobunocephalus iheringii is a small, undemanding fish for its size but needs its specific requirements respected. A tank of 20 US gallons (about 20 US gal) upward is suggested as a minimum, with a soft sand substrate 2–3 inches (2–3 in) deep that lets it burrow and bury itself, which it will do readily and often. Lighting should be kept low or dimmed, since this is a nocturnal fish that is uncomfortable and less likely to be seen under bright conditions; water flow should be slow to moderate. Aim for 72–77 °F and a pH of 6.5–7.5, with regular partial water changes (around 20% weekly) to keep water quality high.
Because it is scaleless, like loaches, puffers and eels it is sensitive to copper and to many standard fish medications — treatments should be dosed conservatively, with a half-dose often recommended as a starting point. It also carries pectoral and dorsal spines, so while not confirmed venomous, it is safest moved in a container rather than netted, avoiding tangling and injury to both fish and keeper. Being reclusive and easily overlooked, it is best kept with calm, small tankmates that will not out-compete it for food after dark, and its presence is easy to underestimate until it is seen foraging at night.
Conservation
Pseudobunocephalus iheringii has not been evaluated by the IUCN Red List, so its conservation status is officially Not Evaluated. This is common for small, geographically restricted, commercially unimportant catfishes that receive little assessment attention despite the broader pressures facing South American freshwater systems.
Its range in the La Plata basin and Laguna dos Patos system faces general pressures typical of the region — habitat degradation, water quality decline and land-use change along smaller tributaries — but no specific population data or threat assessment is available for this species. It is not known to be a significant part of the aquarium trade, which likely limits any collection pressure relative to more commonly exported South American catfishes.