Taxonomy & naming
Bunocephalus hartti was described in 2015 by Carvalho, Cardoso, Friel & Reis as one of two new banjo catfish species from the upper and middle rio São Francisco basin in Brazil, published in a paper on new Bunocephalus from that drainage. It belongs to the family Aspredinidae, the banjo catfishes, within the genus Bunocephalus Kner — a genus of small, flattened, camouflaged South American catfishes. The Catalog of Fishes treats Bunocephalus hartti as the valid name, and no older synonym or reclassification is associated with this comparatively recently described species.
The genus name Bunocephalus derives from Greek roots meaning roughly "mound-" or "knob-headed", a reference to the rough, bumpy texture of the skull common to the genus. The species epithet hartti honours a naturalist associated with the region (the original description does not appear to elaborate at length beyond the dedication). Diagnostically, B. hartti is distinguished from most of its congeners by a pectoral-fin spine that lacks serrations in adults, and by a last dorsal-fin ray that is completely or almost completely fused (adnate) to the back.
Morphology
Bunocephalus hartti has the classic banjo-catfish silhouette: a broad, flattened, disc-like head and forebody tapering into a long, slender, whip-like tail, giving the fish its "banjo" outline. The skin is entirely scaleless and covered in small tubercles and folds rather than smooth skin, and the body pattern is a mottled brown-and-tan camouflage that mimics a dead leaf or a piece of waterlogged bark lying on the riverbed.
Reported maximum size is small — about 2.5 in standard length (FishBase) — genuinely one of the smaller catfishes an aquarist will encounter, and this species does not appear to grow beyond that. As in other banjo cats, the pectoral and dorsal fins carry stiffened spines; unusually for the genus, the pectoral spine in adult B. hartti lacks serrations, a feature used to separate it from close relatives. Even so, the scaleless skin means it should be handled and medicated with the same care given to other naked-skinned catfishes.
Habitat
The species is known only from the upper and middle rio São Francisco basin in Minas Gerais, Brazil, with records from tributaries including the das Velhas, Paraopeba and Formoso rivers. It is a freshwater, strictly benthic species, living on the bottom rather than in open water.
Aspredinids from this basin and its relatives typically occupy marginal backwaters roughly 66–131 ft wide and 1–2 ft deep, over sand-and-clay substrate mixed with accumulated leaf litter — exactly the kind of cover that suits an animal built to look like debris. Water in these habitats runs slightly acidic to near-neutral and soft to moderately hard, on the order of pH 6.0–7.5 and 2–15 dGH, at warm tropical temperatures around 72–81 °F; these figures are drawn from related São Francisco-basin aspredinids rather than measurements specific to B. hartti, so treat them as a close analogue rather than a confirmed reading for this exact species.
Feeding
Banjo catfishes in general are nocturnal benthic omnivores that forage over the substrate after dark for small invertebrates, worms and detritus, relying on barbels and touch rather than sight to find food buried in sand or leaf litter. Bunocephalus hartti has not been studied in detail for diet, but its close relatives fit this pattern closely and there is no reason to expect otherwise.
In the aquarium, congeners such as B. coracoideus take sinking pellets, frozen bloodworm and other small meaty foods readily once settled, and do best when fed after lights-out so a shy, camouflage-dependent fish is not out-competed by faster tankmates at feeding time.
Mating
Specific courtship and spawning behaviour for Bunocephalus hartti has not been documented in the sources available. Among banjo catfishes more broadly, some Aspredinidae — most famously certain Bunocephalus and related genera — are known for females that carry fertilised eggs attached to the belly skin via fleshy stalks (cotylephores) until they hatch, a striking form of external egg-carrying rather than a nest or nursery site. Whether B. hartti follows this pattern specifically has not been confirmed in the available literature, so this should be read as a family-level note rather than a verified fact for this species.
Given the general biology of the group, spawning is likely triggered by seasonal rains and rising water, as reported anecdotally for other Bunocephalus species in the hobby, where large water changes after conditioning on live foods have prompted spawning attempts.
Breeding
Breeding in Bunocephalus hartti is essentially undocumented, and this species has not been reported as bred in the aquarium. Among Aspredinidae broadly, reproduction is known chiefly for the egg-carrying habit described above in some genera, and captive spawning of any banjo catfish remains rare and largely accidental rather than a routine, repeatable hobby practice.
Honest expectations matter here: aquarists should not expect to breed this species, and any successful spawn would be a noteworthy, poorly precedented event rather than something to plan a project tank around. Data on parental care, clutch size, and development time for B. hartti specifically is not available.
In the aquarium
Bunocephalus hartti is genuinely small — to about 2.5 in — so it does not present the size trap that catches out keepers of larger catfish, but it is still a specialist fish. It needs a soft, fine sand substrate it can partially bury into, a thick layer of leaf litter or similar cover to complete its camouflage, and dim lighting; a bare, brightly lit tank leaves it exposed and stressed. Keep it in a calm community with gentle flow rather than boisterous, fast-swimming tankmates that outcompete it for food.
Because its skin is entirely scaleless, it is more sensitive than scaled fish to copper-based medications and many general treatments — dose conservatively, ideally at reduced strength, and avoid copper where possible. It is not aggressive and carries no notable spine hazard beyond the general care warranted by any catfish with fin spines, but as with all cryptic bottom-dwellers, netting can damage its delicate skin and mucus coat, so it is better scooped gently in a container than chased with a net. It feeds and moves mostly after dark, so caves, leaf litter and low light matter more than swimming space.
Conservation
The IUCN Red List assesses Bunocephalus hartti as Near Threatened (assessed 2020). It is a narrow-range endemic of the upper and middle rio São Francisco basin, and its listed threats are declining habitat quality from mining, agriculture and pollution within that drainage.
The basin has also been affected by a major tailings-dam failure at Brumadinho on the Paraopeba River, one of the tributaries where the species has been recorded; the assessment notes this event likely impacted the known collection site there specifically, underscoring how a single localised disaster can bear disproportionately on a species with such a restricted range. There is no significant aquarium trade in this species, and its conservation is tied entirely to the health of its home rivers rather than to collection pressure.