Taxonomy & naming
Auchenipterus dentatus was described by the French ichthyologist Achille Valenciennes in 1840, with a type locality in Guyana. It belongs to the family Auchenipteridae, the driftwood catfishes, a mostly South American group distinguished from other catfish families largely by their unusual internal-fertilisation breeding biology (see Mating). The genus Auchenipterus itself is the namesake genus of the family.
The Catalog of Fishes treats Auchenipterus dentatus as a valid name in the current classification. As with much of Siluriformes, older literature on driftwood catfishes sometimes used different generic placements across the nineteenth and twentieth centuries as the family was worked out; this species has remained in Auchenipterus.
Morphology
Auchenipterus dentatus is a streamlined, laterally compressed catfish built for an active life in open water rather than for hugging the bottom — a departure from the squat, benthic body plan typical of most catfishes. It reaches a maximum recorded length of about 9 in, a genuinely mid-sized driftwood cat that should not be mistaken for a small nano species.
Like all catfishes in this family it is scaleless, with naked, exposed skin — a point that matters directly for medication dosing (see "In the aquarium"). Adult males carry the family's signature trait: the anal fin is modified into an intromittent organ used to transfer sperm internally to the female, unlike the simple fringed anal fin seen in most other catfish.
Habitat
The species is native to South America, recorded from the Corantijn, Suriname, Arataye, Sinnamary and Oyapock river systems of the Guiana Shield — the river drainages of Guyana, Suriname and French Guiana. It favours the more upstream reaches of these rivers.
Unlike most catfish, which hug the riverbed, A. dentatus occupies the upper part of the water column and is most active around dusk, foraging pelagically rather than trawling the bottom. PlanetCatfish.com notes that driftwood catfishes of this genus generally prefer soft, acidic freshwater, consistent with the blackwater and clearwater rivers typical of the Guiana Shield.
Feeding
Auchenipterus dentatus is a nocturnal predator, feeding mainly on insects and small crustaceans according to FishBase, with hobbyist sources adding small fish, insect larvae and other meaty invertebrate prey to the natural diet — it behaves more like an active micro-predator than a bottom-scavenging omnivore.
In the aquarium it takes sinking pellets, frozen foods and other meaty prepared foods readily, but because it is most active after dark, feeding is best timed for dusk or after the lights go out so it is not out-competed by more visible daytime tankmates.
Mating
Auchenipterus dentatus follows the driftwood catfish family's unusual reproductive pattern: internal fertilisation. The male's anal fin is modified into an intromittent organ that transfers sperm directly to the female during mating, rather than the eggs and sperm being released together into open water as in most catfishes.
Following copulation, the female is able to store sperm within her reproductive tract for an extended period. Spawning of the fertilised eggs is reported to begin at the onset of the rainy season, when rising water levels presumably improve conditions for the eggs and fry — the female effectively times egg-laying independently of when mating took place.
Breeding
Because fertilisation is internal and sperm storage lets the female separate mating from spawning, this is not an open-water egg-scatterer in the way most catfishes are, and it is not a species with documented regular captive breeding. Available sources describe the wild reproductive strategy (internal fertilisation, sperm storage, rainy-season spawning) but do not report established aquarium breeding protocols for this species.
Parental care beyond egg-laying is not documented in the sources available; data is sparse on whether either parent guards eggs or fry after spawning. Prospective breeders should treat this as a species better understood for its unusual mating biology than as a home-breeding project.
In the aquarium
This is a mid-sized catfish — up to about 9 in — so it needs a correspondingly long, well-covered aquarium with open swimming space in the upper and middle water column; do not house it as though it were a small nano catfish. As with all driftwood cats its skin is scaleless, making it more sensitive than scaled fish to copper-based medications and some other treatments — dose conservatively.
Provide soft, acidic water with driftwood and cover to mimic its Guiana Shield river habitat, and keep it in a group of four to six, its natural preference according to aquarium care sources. It is a nocturnal fish and is most active at dusk and after dark, so expect it to hide by day; feed accordingly. Like most catfishes it carries stiff fin spines that can lock and snag in a net, so it is best moved in a container rather than netted.
Conservation
Auchenipterus dentatus has not been formally assessed by the IUCN Red List and is listed as Not Evaluated. This is common among smaller, regionally restricted driftwood catfishes that see little targeted conservation research despite occupying a well-defined native range.
Its distribution across the Corantijn, Suriname, Arataye, Sinnamary and Oyapock rivers ties it to the freshwater systems of the Guiana Shield, a region with comparatively intact forest cover relative to much of South America, but specific population trends and threats for this species are not documented in available sources.