Taxonomy & naming
Xyliphius magdalenae was described by the American ichthyologist Carl H. Eigenmann in 1912. It belongs to the family Aspredinidae, the banjo catfishes, within the genus Xyliphius — a small group of flattened, sand-dwelling South American catfishes distinct from the more commonly traded Bunocephalus and Aspredo banjo cats.
The genus name Xyliphius derives from Greek roots referring to wood or a snake-like form, an old descriptive label applied to these elongate, flattened fishes; the species epithet magdalenae refers to the Río Magdalena, Colombia's principal river system and the type locality from which Eigenmann's specimens were collected. The Catalog of Fishes treats Xyliphius magdalenae as the valid combination, and it has not been shuffled among the older catfish genera that swallowed many 19th-century species names.
Morphology
Like other banjo catfishes, Xyliphius magdalenae has the family's signature shape: a broad, flattened, guitar- or banjo-like head and forebody tapering into a slender tail, an outline that mimics a partly buried stone or patch of debris on the riverbed. The skin is scaleless, and the body is covered instead in small tubercles and rough skin typical of aspredinids rather than true bony plating.
Maximum reported size is small — about 3 in standard length — making it one of the more diminutive banjo cats rather than one of the larger Bunocephalus or Aspredo species. As in all catfishes it carries barbels around the mouth used to feel out food on the substrate, and like most Siluriformes it bears spines at the leading edge of its dorsal and pectoral fins; these are stiff and can lock erect, so the fish should be handled with care even at this small size.
Habitat
Xyliphius magdalenae is endemic to the Río Magdalena basin of Colombia, South America's second-largest river system after the Amazon and one that drains a large stretch of the Andes and the northern lowlands before reaching the Caribbean. It is a demersal, freshwater species that lives in direct contact with the riverbed.
Banjo catfishes of this genus are specialised sand-dwellers: their flattened profile lets them bury or press themselves into soft substrate, lying motionless by day and emerging to forage at night. Specific water chemistry data for this species is not well documented in the sources available; general care guidance for the family points to soft, slightly acidic water in the warm range typical of South American lowland rivers, but detailed field measurements for X. magdalenae itself are sparse.
Feeding
As a nocturnal benthic omnivore, Xyliphius magdalenae most likely forages the sand and silt of the riverbed after dark for small invertebrates and organic detritus, in keeping with the feeding style documented across the banjo catfish family. Its flattened, camouflaged body suits an ambush-and-forage lifestyle low over or buried within the substrate rather than active midwater hunting.
In aquarium contexts, banjo catfishes of this type are generally fed sinking foods — pellets, frozen bloodworm and other small prepared foods — offered after lights-out so a shy, nocturnal fish is not out-competed by more active tankmates. Species-specific feeding studies for X. magdalenae were not found in the available sources; this account follows the general Aspredinidae pattern.
Mating
Courtship and spawning behaviour in Xyliphius magdalenae has not been documented in the sources available for this account. Banjo catfishes as a family show varied reproductive strategies, and in several better-studied aspredinids the female carries the fertilised eggs attached to her belly skin via small fleshy stalks (cotylephores) until they hatch — a distinctive form of external egg-carrying rather than nest-building or open-water scattering.
Breeding
Breeding biology in Xyliphius magdalenae is poorly known and not documented in the available sources. Given the pattern seen in other Aspredinidae, egg-carrying by the female — with the fertilised clutch adhering to her belly skin rather than being laid in a nest or scattered over the substrate — is plausible for this genus, but this has not been confirmed specifically for X. magdalenae and should not be assumed as established fact.
The species is essentially unknown in captive breeding; it is rarely if ever kept in the hobby, and there are no reports of successful aquarium spawning to draw on. Anyone encountering this fish should treat its reproduction as an open question rather than expect it to follow a well-worked-out home-breeding protocol.
In the aquarium
Xyliphius magdalenae is a small fish at only about 3 in, but it is a specialised, poorly known species rarely offered in the trade, and anyone considering it should recognise it as a niche, advanced-hobbyist proposition rather than a routine community catfish. A soft sand substrate is essential — this is a fish built to press into and bury in fine sediment, and a bare or coarse-gravel bottom will not suit it. Provide dim lighting and cover, since it is a nocturnal forager that will hide by day.
As with all scaleless catfishes, its naked skin makes it more sensitive to copper-based and some other medications than scaled fish; treat conservatively, at reduced dose, as is standard practice for loaches, puffers, and other scaleless groups. It also carries locking dorsal and pectoral spines that can snag a net, so it is best transferred in a container rather than netted. Given how little is documented about its husbandry, water changes and stability matched to a soft, warm South American lowland river are a reasonable starting point, but keepers should treat this as a fish for careful observation rather than a well-established aquarium subject.
Conservation
The IUCN Red List assesses Xyliphius magdalenae as Least Concern. As an endemic confined to the Río Magdalena basin, its conservation status is nonetheless tied closely to the health of that river system, which faces well-documented pressures elsewhere in its fauna from damming, pollution, and habitat modification across Colombia's most heavily used drainage.
Because the species is rarely encountered in the aquarium trade, collection pressure for the hobby is not considered a meaningful threat; the more relevant long-term concerns are the general environmental pressures facing the Magdalena basin as a whole.