Taxonomy & naming
Tatia aulopygia was described by the Austrian ichthyologist Rudolf Kner in 1858. Like much of Siluriformes, the species has moved between generic combinations over the past century and a half as the family was revised; it is placed today in Tatia within Auchenipteridae, the driftwood catfishes, and the Catalog of Fishes treats Tatia aulopygia (Kner, 1858) as the currently valid combination.
Auchenipteridae sits within the catfish order Siluriformes and is distinguished from most other catfish families by its unusual reproductive anatomy (see Mating, below). The genus Tatia is a moderately diverse group of small South American driftwood cats, several of which — including this species — are occasionally available in the aquarium trade under their scientific name rather than a settled common name.
Morphology
This is a small, slender catfish: FishBase records a maximum of 6.5 in SL from a male specimen (INPA 11080, 4 in SL, collected in the Guaporé river), though most individuals seen in the wild and in the trade run closer to 4 in. As in all catfishes the skin is scaleless, which matters directly for aquarium medication (see "In the aquarium").
Like other driftwood cats, Tatia aulopygia carries stiff, serrated locking spines at the leading edge of the pectoral and dorsal fins — the pectoral spine bears roughly 21–24 forward-pointing (antrorse) serrations along its front edge and backward-pointing (retrorse) serrations toward the tip, with the dorsal spine similarly serrated along its front edge. These spines lock erect and can snag badly in an aquarium net, so the fish is best scooped and moved in a container rather than netted. Females tend to grow bulkier-bodied than males, most noticeably once in breeding condition.
Habitat
Tatia aulopygia is native to the Madeira river drainage of the Amazon basin, recorded from the Guaporé and Mamoré rivers across Brazil and Peru. Like most driftwood cats it shelters by day among submerged wood, root tangles and leaf litter along river margins, emerging to forage after dark.
Reported aquarium water values sit at roughly 70–75 °F with a pH of 6.5–7.5 — a soft-to-neutral tropical river fish rather than an extreme blackwater specialist. Well-oxygenated water with some flow, driftwood, and overhanging cover reproduces the conditions it experiences in its home rivers.
Feeding
In the wild this species forages the bottom and among submerged wood for small invertebrates and crustaceans, feeding mostly after dark like other nocturnal driftwood cats.
In the aquarium it takes frozen bloodworm, sinking catfish tablets, and prawn or shrimp readily, with white worm offered only sparingly as an occasional treat. It feeds enthusiastically once settled, and because it is most active at night, offering food after lights-out ensures it is not out-competed by diurnal tankmates.
Mating
Tatia aulopygia breeds by internal fertilisation, the reproductive strategy that defines the driftwood catfish family Auchenipteridae and sets it apart from almost every other catfish group. The male's anal fin is modified into an intromittent organ used to transfer sperm directly into the female during mating.
Rather than laying and fertilising eggs on the spot, the female stores the sperm internally and does not spawn immediately. Fertile, adhesive eggs are laid on the undersides of submerged wood or similar surfaces some 24–48 hours after mating has taken place — a striking departure from the open-water egg-scattering typical of many other catfish.
Breeding
Because fertilisation is internal and sperm storage does the work of timing the spawn, Tatia aulopygia is one of the few catfish genuinely bred at home without hormone induction or elaborate conditioning. After mating, the female deposits her adhesive eggs on the underside of wood or another submerged surface roughly a day or two later.
Neither parent guards the clutch afterward — parental care is essentially absent once the eggs are laid. In practice the eggs are reported to go unharmed even left in a community tank, since they adhere firmly and are usually left alone by tankmates, though the aquarist wanting to raise a full brood should move eggs or newly hatched fry to a separate rearing tank to maximise survival.
In the aquarium
Tatia aulopygia is a manageable size for a home aquarium — typically around 4 in, up to a recorded maximum of 6.5 in SL — but as with any catfish, size the tank to the adult fish rather than the juvenile sold in the shop. Provide driftwood, roots and shaded hiding places for daytime cover, since this is a nocturnal species that becomes active mostly after dark; feeding after lights-out suits its natural rhythm and prevents it losing out to bolder daytime feeders.
Being scaleless, it is more sensitive than scaled fish to copper-based medications and some other treatments, so dose conservatively — a half-dose approach is often advised for catfish of this kind. It also carries locking, serrated pectoral and dorsal spines that readily snag in a net and can jab the keeper, so it should be moved in a container rather than netted. Kept in soft-to-neutral, well-oxygenated water at 70–75 °F with pH 6.5–7.5, it is a peaceful, undemanding addition to a South American community tank and — unusually among catfish — a species that can actually be bred by a patient home aquarist.
Conservation
The IUCN Red List assesses Tatia aulopygia as Least Concern, most recently in a 2020 assessment. The species is known from a reasonably wide area of the Madeira drainage spanning Brazil and Peru, and no major population threats have been identified.
As with many small, wide-ranging Amazonian fish, formal population monitoring is limited, and ongoing pressures on Amazon basin waterways — deforestation, damming and mining-related sedimentation across the wider Madeira system — remain the long-term concerns for species sharing this range, even where the individual species assessment currently reads Least Concern.