Taxonomy & naming
Ancistrus miracollis was formally described by Bifi, de Oliveira, and Rapp Py-Daniel in 2019 in Neotropical Ichthyology (volume 17, issue 2, e180135). The type series was collected from Igarapé do Mureru, a tributary of the Rio Sucunduri in the Rio Madeira basin, at the highland community of Terra Preta, Apuí, Amazonas State, Brazil (approximately 7°45'45"S, 58°49'00"W). The Catalog of Fishes (Eschmeyer, CAS) recognises Ancistrus miracollis as a valid species under this author combination.
Ancistrus is one of the largest genera in Loricariidae, with more than 70 valid species described and many more awaiting formal treatment. The genus sits in the tribe Ancistrini, subfamily Hypostominae — the same subfamily that contains Panaque, Baryancistrus, and Hypancistrus. Morphological diagnosis within Ancistrus has historically been difficult because so many species share a broadly similar body plan; the discovery of a reliably unique character (the vertical banding) gave the authors a clear anchor for the new species. PlanetCatfish records the species under catalogue number 7479, but at the time of writing no hobbyist sightings or trade records have been submitted there.
Morphology
Adults reach a maximum recorded size of 2.5 in standard length (SL), placing A. miracollis among the smaller members of the genus. The body bears the typical loricariid armour of overlapping bony scutes. The key diagnostic character is the pattern of thin, pale vertical bands crossing the trunk — bands that are sometimes incomplete but are unique among described Ancistrus congeners. This banded coloration immediately separates miracollis from the majority of species in the genus, which carry spotted, reticulate, or plain brown coloration.
Additional diagnostic characters recorded in the original description include a pectoral-fin length that reaches or exceeds the origin of the pelvic fins, a relatively narrow cleithral width (33.5–36.9 % of SL), a reduced dentary width (45.3–54.4 % of interorbital distance), and the presence of an adipose fin — a trait that distinguishes it from the closely related A. verecundus, which lacks an adipose. The mouth is ventrally placed and equipped with fine bicuspid teeth adapted for rasping algae and biofilm from hard substrates.
Sexual dimorphism follows the genus-wide pattern: mature males develop soft, branched tentacles radiating from the snout and the margins of the head, giving them the familiar bristlenose appearance. Females may produce a modest fringe of much shorter tentacles along the snout edge, but the male's display is markedly more elaborate.
Habitat
The type locality and all known collection sites lie in the Sucunduri Dome area of southern Amazonas State — a geologically elevated region where the Rio Sucunduri and its tributaries flow across ancient basement rock before joining the Rio Canumã and ultimately the Rio Madeira. This highland setting produces small, relatively clear or tea-stained streams over rock and sandy gravel, distinct in character from the low-gradient blackwater rivers of the surrounding lowland Amazon.
Specific water chemistry data from collection sites is not available in the published record. Based on the geology and hydrology of the region, Rio Madeira tributaries in this area are typically soft and slightly acidic; streams over highland rock may be somewhat clearer and slightly cooler than lowland blackwater systems. The microhabitat is presumed to be rocky stream bottom and submerged wood, the preferred refuge of most Ancistrus species, where algae and biofilm grow on illuminated surfaces in shallow, swift-flowing reaches.
Feeding
Like virtually all Ancistrus, A. miracollis is primarily a herbivore and biofilm grazer. The fine bicuspid teeth are well-suited to rasping epilithic algae, periphyton, and the microbial films that accumulate on rock surfaces and submerged wood. In slow-growing highland streams, these biofilm communities can be rich in diatoms, cyanobacteria, and detrital organic matter.
No aquarium feeding data exists for this species. By analogy with other Ancistrus — one of the better-studied genera in captive loricariid husbandry — an appropriate diet would include quality algae wafers, spirulina-based foods, and blanched vegetables such as courgette (zucchini) and cucumber. Occasional small invertebrate prey (bloodworm, daphnia) may supplement the diet, though protein-heavy feeding is not a priority. Driftwood should be provided as surface grazing substrate, even if the species is not a true xylophage.
Mating
No courtship observations have been recorded for A. miracollis in the wild or in captivity. The genus-wide pattern is well-documented, however, and likely applies here. Males in breeding condition develop their most elaborate tentacle growth and become strongly territorial around preferred cavity sites — crevices in rock faces, gaps beneath embedded boulders, or hollow wood sections. Males will display to and exclude rival males from the immediate vicinity of a claimed cave.
Females assess males partly by territory quality and cavity condition. When a female approaches, the male may perform fin-spread displays and may position himself at the cave entrance. The male's branched tentacles appear to play a role in species recognition among closely related Ancistrus, particularly in assemblages where several species share the same stream reach. Given the unique vertical banding of A. miracollis, visual signalling during courtship may also be amplified by this pattern.
Breeding
Ancistrus miracollis has not been bred in captivity as of 2026, and no breeding records appear in the hobbyist literature or on PlanetCatfish. General Ancistrus biology strongly suggests cave-spawning with paternal brood care: the male claims a cavity, the female deposits adhesive eggs on the interior walls, and the male remains with the clutch — fanning it continuously with his pectoral and pelvic fins to maintain oxygenation and removing infertile or fungused eggs. Fry of most Ancistrus hatch with a large yolk sac, remaining in the cave until the yolk is absorbed, and begin rasping algae and biofilm almost immediately thereafter.
Given the highland stream origin, conditioning adults with moderate current, well-oxygenated water, and perhaps a slight temperature reduction to simulate cool-season flows may be necessary to induce breeding attempts. Until captive records exist, specific clutch size, incubation duration, and fry rearing conditions remain undocumented.
In the aquarium
Ancistrus miracollis is not known to be available in the aquarium trade as of 2026. PlanetCatfish records no hobbyist sightings, and the species' restricted range in highland Amazonian streams means it is not expected to appear in the ornamental trade in significant numbers. Any specimens entering the hobby would almost certainly be wild-caught research or incidental bycatch exports from the Rio Madeira basin.
If specimens do become available, care requirements can be inferred from its highland stream origin and genus-wide husbandry: well-oxygenated, slightly acidic water (estimated pH 5.5–7.0, temperature 75–82 °F) in a tank furnished with flat rocks and pieces of driftwood that provide both grazing surface and cave refuges. At a maximum of 2.5 in SL, this is a small species that would be manageable in a modestly sized aquarium. A quality algae-based diet supplemented with blanched vegetables would form the nutritional core. Given its novel coloration, A. miracollis would be a highly desirable addition to the hobby should captive-bred stock eventually become established.
Conservation
The IUCN Red List assessed Ancistrus miracollis as Least Concern (LC) in November 2020, the assessment being conducted barely a year after the species was formally described. The listing reflects that no evidence of significant population decline or major threat has been identified within its known range in the Rio Madeira basin.
The Sucunduri and Canumã drainages are relatively remote compared to the more heavily settled parts of Amazonas State, but agricultural expansion, artisanal gold mining (garimpo), and deforestation in southern Amazonia are ongoing pressures across this broader region. Highland stream specialists with restricted ranges are inherently vulnerable to localised habitat degradation; the species' apparent restriction to the Sucunduri Dome area merits continued monitoring. The 2020 LC assessment should be revisited as knowledge of its actual range extent and population size improves.