Taxonomy & naming
Centromochlus altae was described by the American ichthyologist Henry Weed Fowler in 1945. It belongs to the family Auchenipteridae, the driftwood catfishes, within the genus Centromochlus, a group of small South American catfishes distinguished from their larger relatives by their diminutive size and internal-fertilisation breeding biology.
The species has at times circulated under the synonym Duringlanis altae, and older aquarium literature and some retailer listings still use that name. GBIF and current taxonomic treatments place the species firmly in Centromochlus, and that is the valid combination used here. The Catalog of Fishes governs the accepted name; this account keeps Centromochlus altae throughout.
Morphology
Centromochlus altae is one of the smallest catfishes an aquarist is likely to encounter, reaching only about 1.5 in standard length at full maturity — smaller than many tetras. Like other driftwood cats it has a slender, tapering body, a flattened head, and three pairs of barbels used to feel out food and surroundings in the dark. As in virtually all catfishes the skin is naked and scaleless, which has direct consequences for medicating the fish (see "In the aquarium").
The species carries the stiff, serrated pectoral and dorsal spines typical of catfishes generally, though at this size they are fine rather than formidable. A notable feature is sexual dimorphism in the anal fin: males and females differ markedly in its shape, the male's fin being modified into an intromittent organ used to transfer sperm internally during mating.
Habitat
The species is known from the Rio Caquetá basin in Colombia, South America, with its type locality at Morelia. It inhabits floodplain environments typical of Amazonian tributaries — slow, structurally complex water with submerged wood, leaf litter and overhanging vegetation, the kind of cover a fish barely three and a half centimetres long needs to avoid predation.
Water in this part of the upper Amazon system is generally soft and only mildly acidic to neutral. Scotcat's care guide gives a temperature range of 79–82 °F and a pH of 6.5 to 7.5, figures consistent with a warm, stable tropical stream rather than blackwater extremes. Aquarists should avoid pushing the water too alkaline and keep it clean, mirroring the well-oxygenated flowing water of its native floodplain streams.
Feeding
Centromochlus altae is a nocturnal benthic micro-predator and omnivore. In the wild it forages after dark for small invertebrates — ants, beetles and mayflies have all been recorded as natural prey — picking food from the substrate, driftwood surfaces and leaf litter rather than hunting in open water.
In the aquarium it readily accepts frozen bloodworm, small catfish tablets and daphnia. Because it is so small and feeds mainly at night, food is best offered after the lights go out so it is not out-competed by more active daytime tankmates; sinking foods that reach the bottom or lodge in driftwood crevices suit it best.
Mating
Centromochlus altae breeds by internal fertilisation, one of the more unusual reproductive strategies among catfishes. The male's anal fin is modified into an intromittent organ that is used to transfer sperm directly into the female during mating, rather than releasing milt over eggs shed externally as most catfishes do.
Following mating, the female stores the sperm internally and deposits fertile eggs later, reportedly in caves or other sheltered cavities, rather than laying immediately after copulation. This decoupling of mating from egg-laying is characteristic of the driftwood catfish tribe that includes Centromochlus and Tatia, and it sets the species apart from the vast majority of externally fertilising catfishes.
Breeding
Because reproduction relies on internal fertilisation and sperm storage, Centromochlus altae does not fit the typical catfish spawning template of open-water egg-scattering, bubble-nesting or mouth-brooding. The female alone deposits the eggs, in cave-like cavities, some time after mating has occurred, and available accounts do not describe any parental guarding behaviour once the eggs are laid.
Breeding reports for this species in captivity are essentially absent from the available literature — it is rare in the aquarium trade to begin with, and its cryptic, cavity-based egg deposition makes captive spawning difficult to observe or engineer deliberately. Aquarists should treat this as a species that is very unlikely to be bred intentionally at home; sourcing tends to depend on wild collection rather than captive-bred stock.
In the aquarium
This is a genuinely tiny catfish — full-grown adults measure only around 1.5 in — so tank size should be judged by its need for calm, structurally rich water rather than by any size trap; a well-planted nano to small community aquarium with driftwood, leaf litter and dim lighting suits it well. Being scaleless, like nearly all catfishes it is sensitive to copper-based medications and many general remedies; dose conservatively and favour gentler treatments when disease control is needed.
It is nocturnal and secretive, spending daylight hours tucked against wood or under cover, and becomes active only after dark, so tankmates should be equally peaceful and unlikely to bully a fish this small. Reported availability in the aquarium trade is very rare, and the species is described as not dangerous to handle, though as with any catfish it is safer to move it in a net or container rather than grabbing it by hand given its fine locking spines.
Conservation
The IUCN Red List assesses Centromochlus altae as Least Concern, following a 2025 reassessment; the species had previously been listed as Data Deficient in 2020. It is known from the Rio Caquetá basin in Colombia, and the shift to Least Concern reflects improved knowledge of its distribution and status rather than any indication of population decline.
As a small floodplain specialist restricted to a specific Amazonian drainage, its wellbeing remains tied to the health of that river system — habitat degradation, deforestation and water-quality pressures affecting Amazonian tributaries are the general long-term concerns for species with this kind of range, even where the formal assessment is currently reassuring.