Taxonomy & naming
Hypostomus fuscomaculatus was formally described by Zawadzki & Pains da Silva in 2022, in Ichthyological Exploration of Freshwaters (volume 1176, pages 1–11). The type locality is Rio Salobra, Rio Paraguay basin, municipality of Nobres, Mato Grosso State, Brazil (14°38'38"S, 56°16'29"W). The Catalog of Fishes (Eschmeyer, CAS) lists it as a valid species within Loricariidae.
In the hobby the fish was long known under two provisional L-number registrations: L233 (originally assigned in the German magazine DATZ) and LDA009 (assigned in Das Aquarium). Both codes refer to the same taxon. The name LDA009 remains in circulation and is included in the fish's common-name list. Before formal description the species was frequently confused with Hypostomus hermanni, a closely related Mato Grosso pleco; the description resolved this confusion by diagnosing H. fuscomaculatus on the basis of its distinctive live coloration and other characters.
The species belongs to subfamily Hypostominae, tribe Hypostomini. Its distribution encompasses several drainages in Mato Grosso that feed into the upper Paraguay and Paraná systems: the La Plata, Paraná, Paraguay, upper Paraguay, Cuiabá, and Manso basins are all cited in the hobbyist literature as part of its range.
Morphology
Hypostomus fuscomaculatus can exceed 12 in total length (TL), placing it among the larger species in the genus and in the size category that requires substantial aquarium space for long-term maintenance. The body is covered in the typical loricariid scute armour, with the ventrally positioned suckered mouth characteristic of the genus.
The defining feature in life is the coloration: large, widely spaced, dark to black blotches on a pale base colour — the 'eye-spot' or 'dark-spotted' appearance from which its German common name, Augenflecken-Schilderwels (eye-spot armoured catfish), is derived. The species name reflects this directly: fusco (Latin, dark/dusky) combined with maculatus (Latin, spotted or blotched). Importantly, this bold patterning fades quickly in preservative, which likely contributed to historical confusion with the more sombrely marked H. hermanni in museum material.
Sexual dimorphism follows the genus-level pattern: males develop longer fins and more prominent interopercular odontodes, traits used in courtship and territorial competition. Females in breeding condition are broader in the body when viewed from above.
Habitat
The type locality is Rio Salobra in Mato Grosso, a tributary flowing into the Rio Paraguay system at the edge of the Pantanal, the world's largest tropical wetland. Coordinates for the Suedamerikafans database entry place the collection site in the represa da Manso area of the upper Rio Paraguay basin at approximately 14°52'S, 55°47'W — within the broader Pantanal region of Mato Grosso.
The Pantanal and its borderland rivers experience dramatic seasonal flooding. During the wet season (November–March) vast areas of the basin are inundated, and fish communities spread across flooded savanna and forest. Dry-season conditions concentrate fish in main channels and permanent water bodies with higher temperatures and sometimes reduced oxygen. Water parameters recorded for this species in hobbyist sources: temperature 68–82 °F, pH 6.0–8.0 — a broad range consistent with the Pantanal's seasonal chemical variability.
Microhabitat in the Pantanal river system typically includes rocky and gravelly channel substrate, submerged logs and root tangles, and seasonally inundated marginal vegetation. Hypostomus in this region are documented occupying shelter under rocks and in wood piles, emerging to graze at night.
Feeding
Hobbyist sources describe Hypostomus fuscomaculatus as an omnivore with a preference for plant-based foods. In the aquarium it accepts algae tablets, spirulina wafers, blanched vegetables, and frozen invertebrate foods. Green foods form the core of the diet.
In the wild, Pantanal Hypostomus are typically benthic grazers feeding on periphyton, detritus, and biofilm scraped from submerged wood and rock. The omnivore designation reflects observed willingness to consume invertebrate matter opportunistically, as is common across many Hypostomus.
Mating
No specific mating observations have been published for Hypostomus fuscomaculatus. The species has been maintained in the hobby for some years under its L-number codes, but detailed courtship accounts are not documented in the literature available at the time of writing.
Male Hypostomus of this size typically become territorial around potential spawning sites — crevices, under flat rocks, or hollow sections of submerged wood — during the breeding season. Males develop longer fins than females, a secondary sexual trait that likely plays a role in display. Strong filtration is noted as important for captive maintenance, consistent with the metabolic demands of a fish in this size range.
Breeding
No confirmed breeding accounts have been published for Hypostomus fuscomaculatus. The species has been imported and kept in Europe and Brazil under the L233/LDA009 designation, but aquarium spawning records have not been documented in the available hobby or scientific literature. Given its size and Pantanal origin, the species would require a large, well-filtered aquarium with suitable cave or crevice spawning sites. Seasonal temperature drops and variation in rainfall-related parameters may serve as spawning triggers, as seen in related Pantanal loricariids.
In the aquarium
Hypostomus fuscomaculatus has been present in the European aquarium hobby under L233 and LDA009 for some years before its formal description in 2022. Hobbyist sources recommend a minimum aquarium of 71 in in length — roughly 105–130 US gal — for an adult, reflecting the species' potential to exceed 12 in TL.
Water parameters should span the range observed in Pantanal habitats: temperature 68–82 °F, pH 6.0–8.0. The wide tolerance is consistent with a fish from a seasonally variable floodplain system. Strong mechanical and biological filtration is emphasised in hobbyist accounts — large Hypostomus are heavy producers of waste, and water quality must be actively managed to prevent ammonia and nitrite accumulation.
The diet should emphasise green foods: algae wafers, spirulina, blanched courgette (zucchini), cucumber, and similar vegetables. Frozen invertebrate foods can supplement the diet occasionally. Driftwood should be provided both for shelter and as a supplementary grazing surface, though this species is not a wood-specialist in the manner of Panaque or Panaqolus.
Note that the species was previously and sometimes still is sold under the name LDA009 as well as L233; buyers should be aware that both codes refer to the same fish. It has historically been confused with H. hermanni, which it superficially resembles in preserved form; live fish with bold dark blotches are more likely to be H. fuscomaculatus.
Conservation
Hypostomus fuscomaculatus has not been evaluated by the IUCN Red List and carries no formal conservation status. Its range in the upper Paraguay basin and Pantanal borderlands of Mato Grosso encompasses a region under significant land-use pressure. Mato Grosso is Brazil's largest soy-producing state; agricultural expansion, deforestation, and infrastructure development (dams, roads) pose ongoing threats to headwater and riverine habitats across the drainage.
The Pantanal itself is increasingly affected by drought intensification linked to deforestation in the surrounding cerrado, altering the flood pulse that drives the ecosystem. Changes in seasonal flooding patterns affect the habitat complexity on which benthic loricariids depend. As a species now formally named and with documented hobby interest, H. fuscomaculatus warrants a formal IUCN assessment to establish baseline population status before more detailed trend data are required.