Taxonomy & naming
Hypostomus brevis was originally described by John Treadwell Nichols in 1919 as Plecostomus brevis, based on a single specimen — the holotype deposited at the American Museum of Natural History (AMNH 7150), measuring 3 in standard length. The Catalog of Fishes (Eschmeyer, CAS) recognises the current valid combination Hypostomus brevis, with Plecostomus brevis Nichols 1919 as the original basionym.
The type locality is recorded as Estado de São Paulo, Brazil, with some sources associating the species with the Paraná River basin or possibly an eastern Brazilian coastal drainage — the exact basin affiliation remains uncertain given the holotype-only basis of the description. No revision has resolved this ambiguity to date.
It should be noted that the epithet brevis is also used for a separate catfish species, Peckoltia brevis, within the same family Loricariidae. These are genuinely distinct species in different genera; care should be taken not to conflate records.
Morphology
The holotype measures 3 in standard length, making H. brevis a small species by Hypostomus standards. The species name — from Latin brevis, meaning 'short' — was applied by Nichols in direct reference to what he noted as its very short body form, an unusual proportional character among its congeners.
Beyond the single holotype, detailed morphological data for H. brevis are not available in the accessible literature. Like all members of Hypostomus, it would bear the family's characteristic heavy armour of keeled, overlapping odontode-bearing scutes covering the head and flanks, a broad ventrally positioned sucker mouth, and a heterocercal caudal fin. Hypostomus species are facultative air-breathers, capable of supplementing gill respiration by gulping atmospheric air into a modified stomach when dissolved oxygen is low — a trait that likely applies here given its family membership.
Data are too sparse to characterise coloration, fin-ray counts, or plate series for this species.
Habitat
Reliable habitat data for H. brevis are absent from the primary literature. The holotype was collected from Estado de São Paulo, Brazil, though the precise water body and environmental conditions at the collection site are unrecorded. The basin affiliation — whether Paraná drainage or a coastal river system — has not been confirmed from specimens collected after 1919.
Based on the known distribution of related Hypostomus species in southeastern Brazil, the species likely inhabits flowing freshwater systems — rivers, streams, or their tributaries — over rocky or sandy substrates in tropical or subtropical conditions. No temperature, pH, or water-chemistry measurements are available for this species specifically.
Feeding
No feeding observations for H. brevis in the wild or in captivity are documented. As a member of Hypostomus, it almost certainly feeds in the manner typical of the genus: scraping aufwuchs (algae, periphyton, and associated microorganisms) and fine organic detritus from submerged hard surfaces using its specialised teeth and sucker mouth. Many Hypostomus species also ingest fine sediment along with biofilm material.
In the absence of species-specific data, dietary inferences rest on general loricariid biology and should be treated as provisional.
Mating
No mating behaviour has been recorded for H. brevis. Hypostomus species are generally cave-spawners or crevice-spawners, with males selecting and guarding nest sites. Whether this applies to H. brevis cannot be confirmed from available records.
Data sparse.
Breeding
No breeding data exist for H. brevis in the wild or in captivity. The species has not been recorded in the aquarium trade, and no captive spawning reports are known.
Data sparse.
In the aquarium
Hypostomus brevis is not known from the aquarium trade and no husbandry records exist. Given that the species is known only from a century-old holotype of uncertain provenance, it is unlikely to have been collected for ornamental purposes. Any care information would be purely speculative based on its genus membership.
Data sparse.
Conservation
The IUCN Red List assessed Hypostomus brevis as Data Deficient in 2018. This designation reflects the fundamental problem of a species known from a single specimen collected in 1919: without confirmed additional records, it is impossible to assess population size, range, or threat status. The type locality in Estado de São Paulo, Brazil is not precisely documented, preventing targeted surveys.
Southeastern Brazil's river systems have experienced substantial habitat modification over the twentieth and early twenty-first centuries — deforestation, agricultural runoff, river channelisation, and dam construction are all documented pressures in the region. Whether any of these threats affect H. brevis populations that may exist but are as yet undetected cannot be determined. The species may be genuinely rare or may simply be under-surveyed; the Data Deficient status reflects this irreducible uncertainty.