Taxonomy & naming
Hypostomus faveolus was formally described by Cláudio H. Zawadzki, José L. O. Birindelli, and Flávio C. T. Lima in 2008, in volume 6, number 3 of Neotropical Ichthyology (pages 395–402). The holotype (MZUSP 101174) was taken from the Corixo da Saudade, a tributary of the Rio Araguaia drainage within the Tocantins basin, 16 mi north of Cocalinho on road MT 136, Mato Grosso state, Brazil (14°17'20.6"S, 51°09'12.1"W). The Catalog of Fishes (Eschmeyer, CAS, spid 70588) accepts Hypostomus faveolus Zawadzki, Birindelli & Lima 2008 as valid; no synonyms are listed.
Prior to its formal description, the species had circulated in the German aquarium magazine coding system as L037 (and independently as L037a), and in das Aquarium magazine as L161; PlanetCatfish lists all three codes under the single valid taxon. It was also sometimes mislabelled in the trade under L037a when Xingu-basin specimens were assigned a separate provisional identity based on geographic colour variation.
Within the mega-diverse genus Hypostomus (over 140 valid species), H. faveolus is tentatively placed in the H. plecostomus species group based on intermediate dentary tooth size and crown morphology, though the phylogenetic position of many Hypostomus species groups remains under active revision. The species belongs to subfamily Hypostominae (Armbruster, 2004).
Morphology
Hypostomus faveolus attains a maximum standard length of 8 in (the holotype; PlanetCatfish records up to 8 in SL; total length approximately 10–12 in in preserved specimens including the caudal fin). The body is elongate and dorsoventrally depressed, covered by five rows of moderately spinulose dermal plates bearing odontodes (25–26 in the dorsal series, 25–27 in the mid-ventral and ventral series). The head is broad and rounded anteriorly with a conspicuous median mesethmoid bulge. The abdomen is fully plated. Conspicuous keels run along the predorsal plates (three plates) and the lateral plate rows, enhancing structural rigidity.
The dorsal fin bears one unbranched spine and seven branched rays (I,7); when adpressed, the posterior rays reach to or nearly to the preadipose plate. Pectoral spines are robust (I,6) with distally increasing odontodes. The caudal fin has a forked, slightly concave margin with a longer lower lobe (16 principal rays). The adipose spine is small and compressed.
The defining character is coloration: pale, large, rounded blotches outlined by narrow dark margins on a darker brown background — a pattern unique among common Hypostomus in being reversed relative to the typical dark-spots-on-pale arrangement. In life the blotches have a distinctly yellowish cast, intensifying the honeycomb appearance. Geographic variation is consistent: Xingu specimens tend to have broader dark margins around the blotches (creating a bolder net pattern), while Tocantins individuals show narrower dark limits and more prominent pale areas. Juveniles from the Xingu may show vermiculated pale markings on the head that coalesce into discrete blotches with age.
Sexual dimorphism follows the hypostomine pattern: mature males develop elongated odontodes on the pectoral spines and interoperculum; females are proportionally broader across the body when gravid.
Habitat
Hypostomus faveolus is endemic to central Brazil, occurring in the Tocantins River basin — including the Araguaia and its tributaries (rio das Mortes, Vermelho, Água Fria, Pindaíba, Paranã, and others) — and in the upper Xingu River basin, including the Culuene, Suiá-Miçu, Ronuro, and Jatobá drainages. The range spans the states of Mato Grosso, Goiás, Tocantins, and Maranhão. A single record from the rio Meia Ponte (upper Paraná basin) is likely attributable to human-mediated introduction rather than natural range.
The species is eurytopic — occupying a wide spectrum of freshwater microhabitats. Adults are found in both fast-flowing rapids and slower river reaches of medium to large rivers over rocky or sandy substrates. Juveniles characteristically use calmer peripheral habitats: oxbow lakes, lateral pools, and small tributary streams. This habitat breadth is unusual among loricariids and has likely contributed to the species' relatively wide native range within the cerrado-transition zone of central Brazil.
Water parameters from collecting localities reflect the clear, seasonally variable rivers of the central Brazilian plateau: temperature 73–81 °F (PlanetCatfish), pH approximately 6.0–7.2, soft to moderately hard water. During the Tocantins and Araguaia flood pulse, habitat connectivity expands substantially; during the dry season the species concentrates in permanent river channels and rocky rapids.
Feeding
Hypostomus faveolus feeds principally on algae, periphyton (aufwuchs), and detrital organic matter scraped from hard substrates — the standard hypostomine grazer diet. The ventral sucker mouth with its papillate lips and multiple rows of bicuspid teeth is ideally suited to rasping biofilm and attached algae from the rocky substrate of rapids habitats. Fine organic matter ingested with the biofilm provides significant caloric input alongside the algal fraction.
Facultative air-breathing, documented for the genus Hypostomus broadly, allows H. faveolus to exploit the seasonally oxygen-depleted oxbow lakes and lateral pools where juveniles are commonly found. Surfacing behaviour and intestinal air-breathing supplement branchial respiration under hypoxic conditions, enabling survival in isolated dry-season pools.
In the aquarium, H. faveolus proves a willing and effective feeder. Its preferred foods are algae wafers, spirulina-based sinking discs, and blanched vegetables (courgette, cucumber, sweet potato, peas). Bogwood is recommended both for rasping and for the digestive fibre and biofilm it supplies. Occasional meaty supplements — bloodworm, artemia, small carnivore pellets — are accepted but the diet should remain primarily plant-based. Consistent algae control in the tank is one of the species' practical benefits for hobbyists.
Mating
No courtship observations specific to Hypostomus faveolus have been published, and PlanetCatfish records no breeding reports for the species. Based on the general biology of Hypostominae and on its size class, the mating system is expected to follow the cave-spawning, male-territorial pattern typical of mid-sized Hypostomus: males establish and defend territories around preferred spawning sites — rock crevices, undercut ledges, or cavities in submerged wood — displaying to rivals and to females through lateral threat postures and the extension of evertible interopercular odontodes.
Breeding-condition males of Hypostominae develop noticeably elongated odontodes on the pectoral spines and cheek plates, which function both in male–male competition and likely in mate assessment. Females entering peak reproductive condition become visibly broader-bodied when viewed from above, reflecting developing ovaries. The seasonal trigger in the wild is linked to the wet-season flood pulse — rising water levels, cooler temperatures, increased oxygen, and expanding habitat access have all been implicated across the family.
Intraspecific aggression between males is expected in a confined space; multiple males in a mid-sized aquarium without sufficient cave resources and visual barriers will engage in extended fin-spreading and, occasionally, physical contact.
Breeding
Hypostomus faveolus is a cave-spawner with paternal brood care, following the standard Hypostominae reproductive template. No captive breeding has been formally published in the English-language hobby literature as of this writing, and PlanetCatfish carries no breeding reports. A successful spawn is documented in the German Catfish Study Group (CSG) Journal 2021 issue 2, suggesting that reproduction in a large, well-conditioned aquarium is achievable under the right conditions.
In nature and in successful aquarium spawns for related species, the male selects and defends a suitable cavity — a rock cleft, a ceramic breeding cave, a hollow section of hardwood — and deposits and guards a clutch of adhesive, pale-coloured eggs. The male fans continuously to maintain oxygen supply and removes infertile material. At typical tropical temperatures (77–81 °F), incubation is approximately 5–7 days. Fry emerge as miniature armoured juveniles and begin grazing on algae and biofilm within days; the male's guarding intensity decreases as the fry become mobile and begin to disperse.
Replicating the conditions likely to trigger spawning involves a large tank (300+ litres), well-oxygenated flowing water, multiple structured caves, varied conditioning diet over several months, and a simulated wet/dry seasonal cycle with a modest temperature swing of 36–37 °F.
In the aquarium
The Honeycomb Pleco's adult size of up to 8–10 in total length places it in the practical mid-range of aquarium plecos — substantially smaller than the 15.5–19.5 in Pterygoplichthys commonly sold as 'common plecos', but too large for tanks under 40 US gal. A comfortable long-term setup for a single adult requires a minimum of 50–55 US gal; if multiple individuals are intended, 80 US gal with clearly differentiated cave territories is more appropriate, particularly for males.
Water parameters should match the central Brazilian rivers of origin: temperature 73–81 °F, pH 6.0–7.2, soft to moderately hard water (GH up to ~12°dH). The species does not demand extreme water softness but will be at its best in dechlorinated, well-filtered, moderately oxygenated water. Strong filtration is essential — a 8 in loricariid produces significant organic waste and has considerable biological oxygen demand.
Decoration should include several caves or overhangs (clay pots, ceramic caves, flat rock stacks), driftwood for rasping, and open sandy or gravel areas for foraging. Subdued lighting and areas of plant coverage suit the nocturnal activity pattern. H. faveolus is peaceful toward dissimilar tank inhabitants and shows the standard Hypostominae tolerance for most community fish; aggression is generally reserved for conspecific males or very similar-looking pleco species competing for cave space.
The species is available as a specialty import, appearing sporadically in the pleco trade under the L037 code. Pricing reflects its limited availability; captive-bred specimens are rare.
Conservation
Hypostomus faveolus was assessed as Least Concern by the IUCN Red List in 2018 (the most recent assessment), based on a relatively wide distribution across the Tocantins-Araguaia and upper Xingu drainage systems of central Brazil and the absence of documented population-level declines at the time of assessment.
However, the species' geographic footprint places it squarely within two river systems that have experienced significant hydroelectric development and deforestation pressure. The Tucuruí Dam on the lower Tocantins — completed in 1984 and one of the largest hydroelectric reservoirs in the world — dramatically altered the river's flow regime, eliminated rapids ecosystems downstream of the dam, and inundated large areas of the middle Tocantins. The Belo Monte complex on the Xingu, operational since 2016, poses an analogous threat to upper Xingu populations. Loricariid species dependent on rocky rapids — as H. faveolus adults are — are particularly vulnerable to these alterations, and local extirpations from modified rapids sections have been documented for rheophilic loricariids in the region.
The aquarium trade is unlikely to represent a significant conservation pressure at current collection volumes, and the species' broad habitat use across the basin's remaining intact river reaches provides some resilience. Continued monitoring of Tocantins and Xingu populations as dam impacts accumulate is warranted.