Taxonomy & naming
Microglanis pataxo was described in 2006 by Sarmento-Soares, Martins-Pinheiro, Aranda and Chamon, with the type locality in the Rio Peruípe basin in Bahia state, Brazil. It belongs to the family Pseudopimelodidae, the bumblebee and dwarf-pimelodid catfishes, a scaleless group historically confused with the true Pimelodidae before being split out on the strength of skeletal and skin characters.
The description marked the first confirmed record of the genus Microglanis in the coastal river systems of northeastern Brazil, well outside the genus's better-known Amazon and Paraná-basin range. The specific epithet pataxo honours the Pataxó, an indigenous people of southern Bahia and northern Espírito Santo, whose traditional territory overlaps the rivers where the species was found. As with other members of the genus, older literature occasionally shuffled small pseudopimelodids among Pimelodus- or Microglanis-adjacent names, but Microglanis pataxo has held as the valid combination since its description.
Morphology
This is a genuinely small catfish: the maximum recorded size is only about 1.5 in standard length, smaller than many tetras it might share water with. The body follows the typical bumblebee-catfish plan — a broad head, tapering body and long sensory barbels — with a dorsal fin of seven soft rays and 29 vertebrae in the original description. The pectoral spine carries a serrated posterior border, a detail shared with many small pimelodid-type catfishes and one that matters for handling (see below), and the fish has a comparatively narrow head and seven pleural ribs, characters used to separate it from close relatives.
Like all pseudopimelodids, Microglanis pataxo has no scales at all — its skin is bare, giving the mottled, often bumblebee-like coloration typical of the genus. Because the species was described relatively recently and is known mainly from taxonomic literature, detailed live-colour notes are sparse; expect the dark-mottled-on-pale pattern typical of small Microglanis rather than any striking novel colouration.
Habitat
Microglanis pataxo is known only from small rivers in the lower and middle Rio Peruípe, the middle Rio Jucuruçu, and the Rio Cahy basin — three neighbouring coastal drainages in Bahia state, northeastern Brazil. This is a tight, single-region endemic rather than a wide-ranging Amazonian species, and nothing in the available literature suggests it occurs anywhere else.
Specific water chemistry data for the type rivers themselves is sparse in the sources available. Related small Microglanis from similar South American coastal and lowland drainages are generally kept in warm, soft, mildly acidic water, and that is a reasonable working assumption here, but hobbyists should treat exact figures as a genus-level approximation rather than a measurement from the Peruípe, Jucuruçu or Cahy rivers themselves.
Feeding
As with other small Microglanis, this is almost certainly a nocturnal, bottom-dwelling micro-predator and scavenger, foraging after dark over the substrate for small invertebrates and organic material rather than actively hunting in open water. Direct dietary data for Microglanis pataxo has not been published in accessible sources, so this account follows the well-documented feeding pattern of its closest relatives.
In the aquarium, related small Microglanis accept any food of a suitable size — sinking pellets, small frozen foods such as bloodworm or brine shrimp, and other prepared foods — without being fussy, and they are not known to damage plants. Because they are nocturnal foragers, feeding after lights-out gives the fish a fair chance against faster daytime feeders.
Mating
No courtship or spawning behaviour has been documented for Microglanis pataxo specifically; the species is known essentially from taxonomic collections rather than from long-term husbandry. Data is sparse enough that nothing meaningful can be said about pairing or courtship for this species beyond what is known of its close relatives, where spawning has occasionally been observed with eggs simply deposited among plants rather than through any elaborate courtship display.
Breeding
Breeding has not been documented for Microglanis pataxo in the aquarium or, as far as available sources show, in the wild beyond its basic reproductive biology. Do not assume open-water egg-scattering or any other specific mode for this species — the data simply is not there.
For context, related small Microglanis are only rarely bred in captivity: on the odd occasion it has been reported for genus relatives, eggs were deposited on plants with no parental care afterward. Given how recently Microglanis pataxo was described and how narrow its known range is, it should be treated as effectively unbred in the hobby, and any claim of achieved captive breeding for this exact species should be treated with real skepticism until documented.
In the aquarium
Microglanis pataxo stays genuinely tiny — about 1.5 in as an adult — so it is one of the rare catfish where the usual "size trap" runs the other way: this is not a fish that will outgrow a modest tank, but it is also delicate enough that it needs a stable, mature setup rather than a rough starter tank. A small planted aquarium with soft substrate, leaf litter or driftwood cover, and dim lighting suits its nocturnal habits; expect it to hide by day and forage after dark.
Being scaleless, it is medication-sensitive in the same way as loaches, puffers and eels — dose copper-based treatments and many standard medications conservatively, often at half strength, and prefer non-chemical treatment where possible. The pectoral spine is serrated and can catch in a soft net, so it is safer to move the fish in a container. As an uncommonly kept, only recently described micro-catfish, it should be sourced with care about provenance, and given its narrow natural range and small size it is best suited to a peaceful nano or species setup rather than a boisterous community.
Conservation
Microglanis pataxo has not been evaluated by the IUCN Red List and carries no formal conservation status (Not Evaluated). It is known only from a small number of coastal river drainages in Bahia, Brazil — the Rio Peruípe, Rio Jucuruçu and Rio Cahy basins — which by itself makes it a narrow-range endemic of a kind that tends to be vulnerable to local habitat degradation, even without a formal assessment confirming it.
Coastal Atlantic Forest drainages in Bahia face pressure from agriculture, deforestation and water extraction, and a fish restricted to just three small river systems has little room to absorb habitat loss in any one of them. No trade or captive-breeding programme is documented for this species, so its status in the aquarium hobby, if any, is essentially incidental rather than established.