Taxonomy & naming
Tatia gyrinus was described by Carl H. Eigenmann and William Ray Allen in 1942 as Centromochlus gyrinus, from the Río Itaya near Iquitos, Peru. It was later transferred to the genus Tatia, where it is placed today; the Catalog of Fishes treats Tatia gyrinus as the valid combination. It belongs to the family Auchenipteridae (driftwood catfishes) and the subfamily Centromochlinae.
The species epithet gyrina derives from the Latin/Greek gyrinos, "tadpole", a reference to the fish's rounded, tadpole-like body outline — a stubby head and trunk tapering to a slender caudal peduncle. The genus name Tatia has no strong classical derivation and is treated as an arbitrary generic name coined for the group. As in much of Siluriformes, older literature and some aquarium sources may still list this species under its original combination, Centromochlus gyrinus; Tatia is the name in current use.
This fish was long listed as Tatia gyrina; Eschmeyer's Catalog of Fishes now treats that name as a synonym of Tatia gyrinus, the valid name followed here.
Morphology
This is a genuinely small catfish: FishBase records a maximum of just 1.7 in SL, and specimens examined in the taxonomic revision of the genus (a male of 1.19 in SL from Suriname, a female of 1.02 in SL from Tefé, Brazil) confirm that most individuals stay well under that ceiling. The body is short and rounded — the "tadpole" shape referenced in its name — with a blunt head, three pairs of barbels, and a small adipose fin ahead of the tail typical of the family.
Like other Auchenipteridae it is scaleless, with naked skin rather than the bony plating seen in Loricariidae or Callichthyidae. It carries the stiff, serrated, lockable pectoral and dorsal spines typical of catfish; these can catch in aquarium nets, so this species — small as it is — is still best scooped with a container rather than netted. Colouration is a mottled brown to grey-brown, offering camouflage against wood and root tangles.
Habitat
Tatia gyrinus is native to the upper and central Amazon basin, recorded from Peru, Colombia, Brazil and Suriname, with its type locality at the Río Itaya near Iquitos, Peru. It lives in Amazonian streams and river margins, sheltering by day among driftwood, submerged roots and leaf litter — the tangled cover that gives the driftwood catfish group its common name.
Water in these habitats runs warm and on the soft, acidic side: FishBase gives a temperature range of 70–75 °F and pH 6.5–7.5, consistent with the blackwater and soft river conditions typical of much of its Amazonian range. These figures, not a blanket assumption, should guide aquarium water chemistry for the species.
Feeding
Tatia gyrinus is a nocturnal benthic omnivore. In the wild it forages over the bottom and among submerged wood after dark, picking off small invertebrates, insect larvae and other tiny prey items, likely supplemented with detritus and organic material given its omnivorous habits noted by aquarium sources.
In the aquarium it accepts sinking pellet and flake foods along with frozen fare, but being tiny and strictly nocturnal it does best when fed after lights-out, once more boisterous, day-active tankmates have settled — otherwise it can be out-competed for food despite being an easy eater in principle.
Mating
Tatia gyrinus follows the distinctive reproductive strategy of the driftwood catfish family: internal fertilisation. The male's anal fin is modified into an intromittent organ used to transfer sperm directly to the female during copulation, rather than releasing milt over a scattered clutch as most catfish do. Mating itself takes place internally and briefly, with no extended courtship display recorded.
What follows is the more unusual part: the female can store the received sperm and use it to fertilise and lay a clutch of eggs at a later date — potentially days or weeks after mating, without the male present at the time of spawning. This decoupling of mating from egg-laying is rare among catfishes and is one of the defining features of Auchenipteridae reproduction.
Breeding
Because fertilisation happens internally and spawning can be deferred, breeding this species in the aquarium is unpredictable and not well documented as a routine home project. Sexual dimorphism is limited to build — males are described as slimmer-bodied than females — which offers a rough way to sex adults but little else to plan a spawn around.
Set facts.breeding.mode reflects the known biology accurately: internal fertilisation via the male's modified anal fin, with the female storing sperm and laying fertile eggs later. There is no reported parental care after the eggs are laid; unlike the bubble-nesting callichthyids or guarding ictalurids, Tatia gyrinus does not appear to protect its clutch. Aquarists should treat successful captive breeding as opportunistic rather than something to be deliberately engineered with confidence.
In the aquarium
At barely 1.7 in maximum, Tatia gyrinus is genuinely nano-sized and suits a modest species or community tank — around 15–16 US gal upward with plenty of driftwood, roots and leaf litter to replicate its natural cover, since it is shy and largely nocturnal, hiding by day and emerging after dark to forage. It is peaceful and easily overlooked or outcompeted by larger, bolder tankmates, so it pairs best with other small, calm fish.
Being scaleless, it is medication-sensitive in the same way as loaches, puffers and other naked-skinned catfish: dose copper-based treatments and many standard medications conservatively, often at half strength, and monitor closely. Its small size does not remove the netting hazard from its locking pectoral and dorsal spines — a soft container is safer than a net for moving it. Match water chemistry to its wild range: warm, soft and mildly acidic (around 70–75 °F, pH 6.5–7.5), not the harder or more alkaline water suited to many other South American catfish.
Conservation
The IUCN Red List assesses Tatia gyrinus as Least Concern. It has a fairly broad range across the upper and central Amazon basin, spanning parts of Peru, Colombia, Brazil and Suriname, and it is not currently considered at risk.
As with many small, cryptic Amazonian catfishes, detailed population data is sparse, and its conservation outlook is best understood as tied to the general health of Amazonian streams and blackwater habitats — deforestation, water quality changes and habitat disturbance across its range are the sort of long-term pressures that could affect it, even though no specific threat has driven a higher-risk assessment.