Taxonomy & naming
Microglanis ater was described by Ernst Ahl in 1936. It belongs to the genus Microglanis, part of the family Pseudopimelodidae — the bumblebee or dwarf pimelodid catfishes, a group that was long lumped into the Pimelodidae before being split out as its own family. Microglanis is the most widely distributed genus in Pseudopimelodidae, with species scattered from the Guianas and Venezuela across the Orinoco and Amazon basins to the Río de la Plata drainage and Brazil's eastern coastal rivers.
The type locality given for Microglanis ater is central Brazil ("Mittelbrasilien" in Ahl's original German). The Catalog of Fishes (Eschmeyer, CAS) is the standing authority for the valid combination Microglanis ater; data on this species remain sparse compared with the well-studied M. iheringi, and no recent taxonomic revision specific to it was found in the cache used for this article.
Morphology
Microglanis ater has the classic bumblebee-catfish silhouette: a broad, flattened head, a stout, tapering body and a wide mouth flanked by barbels, built for engulfing prey rather than for speed. Maximum recorded size is small — about 3 in standard length — making it one of the more modest members of a genus whose species mostly stay under 4 in.
As in all pseudopimelodids the skin is scaleless (naked), which is directly relevant to husbandry: scaleless catfish absorb dissolved medications more readily through unprotected skin and can reach higher tissue concentrations than scaled fish, so dosing needs to be conservative (see "In the aquarium"). Like most catfish it also carries stiffened, lockable spines at the leading edge of the dorsal and pectoral fins, which can snag in a net.
Habitat
Microglanis ater is a Brazilian freshwater species, with its type locality in central Brazil. Its genus Microglanis is thinly but broadly spread through South American lowland river systems — the Guianas, Orinoco, Amazon, Río de la Plata and Brazil's eastern coastal drainages — but the specific rivers and habitat details for this species are not well documented in the sources available.
General care literature for the genus describes Microglanis species as undemanding about water chemistry, tolerating a range of tap-water conditions, with softer, slightly acidic water preferred specifically for breeding attempts. Data on this species' precise wild habitat (river type, substrate, vegetation) is sparse; treat any specific claim beyond "Brazilian freshwater" with caution.
Feeding
Microglanis ater is a nocturnal, bottom-dwelling predator and scavenger, the typical bumblebee-catfish strategy: it hides during the day and forages after dark for anything it can overpower, including invertebrates and smaller fish. Care sources describe the genus as greedy, with fish up to roughly half the catfish's own body length regarded as fair game — a real consideration when choosing tankmates.
In the aquarium it takes sinking pellets, tablet foods and frozen items such as bloodworm readily, along with a variety of small prepared foods. Because it feeds mainly at night, offering food after the lights go out helps ensure it gets fed rather than being out-competed by diurnal tankmates.
Mating
Specific courtship behaviour for Microglanis ater is not documented in the sources available for this article. General accounts of the genus note that spawning is associated with softer, slightly acidic water, which is thought to be the trigger or preferred condition rather than a strict requirement for day-to-day keeping. Beyond that, detailed mating behaviour — pairing, courtship displays, spawning site selection — is data sparse for this species and should not be assumed from other catfish groups.
Breeding
Breeding is confirmed but rarely practiced and not well documented for this species. Available accounts describe the genus laying eggs scattered onto plants with no parental care from either parent afterward — unlike the armoured callichthyid catfishes (bubble-nesting) or the driftwood catfishes (internal fertilisation), Microglanis does not guard its brood. Softer, slightly acidic water is cited as the condition associated with successful spawns.
Because reports are thin and largely generalised from the genus rather than this specific species, keepers should treat Microglanis ater as a fish that is occasionally bred incidentally in a well-matured, densely planted tank rather than one with an established, repeatable home-breeding protocol.
In the aquarium
Microglanis ater stays small — about 3 in — so it is manageable in a modestly sized aquarium, but its adult size should still be respected when planning tankmates and hiding spots; do not assume a fish this size is harmless to anything smaller. It is undemanding on water chemistry and adapts to a range of tap-water conditions at stable temperatures in the low-to-mid 20s °C, with softer, slightly acidic water favoured if breeding is the goal.
Being scaleless, it is more sensitive than scaled fish to copper-based medications and some other treatments; a conservative approach (often a half-dose, with careful monitoring) is advised, echoing the same caution given for loaches, puffers and other naked-skinned catfish. It also carries locking pectoral and dorsal spines that can snag a net, so it is best scooped in a container rather than chased with a net. Provide caves, wood or dense cover for daytime hiding, since it is a nocturnal fish that becomes active mainly after dark, and keep tankmates large enough that they are not viewed as a meal — the rule of thumb from the genus is that anything up to about half the catfish's length is at risk.
Conservation
Microglanis ater has not been evaluated by the IUCN Red List (Not Evaluated); no species-specific conservation assessment was found for it. This is common for small, poorly studied Neotropical catfishes with restricted or under-surveyed ranges. A related, better-known congener, M. iheringi, is assessed as Least Concern, but that status cannot be extended to M. ater without a dedicated assessment.
Without population trend data or a formal assessment, the conservation status of Microglanis ater in the wild is essentially unknown. As with many similarly obscure single-region catfishes, the main practical note for aquarists is that any specimens in the trade should be assumed to be of uncertain origin unless a supplier states otherwise.