Taxonomy & naming
Hisonotus alberti was formally described by Roxo, Silva, Waltz & Melo in 2016 in Zootaxa (volume 4109, number 2, pages 227–238), from a holotype collected at Ribeirão das Posses, a tributary of the upper Rio Paraná basin in Minas Gerais state, Brazil. The holotype (MZUSP 118845) is an adult male measuring 1.5 in SL, taken on 19 May 2011 in the municipality of São Roque de Minas (approximately 20°17′15″S, 46°34′53″W).
The Catalog of Fishes (Eschmeyer, CAS) recognises Hisonotus alberti as a valid species. Roxo et al. placed the genus in subfamily Otothyrinae in the original description; FishBase and many subsequent authors assign the same group to Hypoptopomatinae, reflecting unresolved but ongoing subfamily-level revision within Loricariidae. The species has no registered L-number and does not appear to have entered the ornamental trade under any popular name.
Morphology
Adults of H. alberti reach a maximum recorded standard length of 1.5 in SL — a size comparable to the smallest otocinclus. The most diagnostically striking feature is the abdomen: it is completely exposed, bearing no development of dermal plates whatsoever. This is explicitly noted in the species description as a key character separating it from congeners with partial or full abdominal plating.
The head lacks conspicuous crests, with the exception of a small tuft of enlarged odontodes located at the posterior tip of the parieto-supraoccipital region. The anterior snout margin is fully covered by both dorsal and ventral odontode series. Beyond these diagnostic characters, the body plan follows the typical hypoptopomatine pattern: dorsoventrally flattened, rhomboid in cross-section, with the suckermouth positioned ventrally for grazing on hard substrates. No significant sexual dimorphism is documented for this species.
Habitat
This species is known from two drainage systems in central Brazil: the upper Rio Paraná basin (the type drainage) and the Rio São Francisco basin, both in Minas Gerais state. These are upland river systems with clear, fast-flowing headwater streams typical of the Brazilian cerrado and Atlantic Forest transition zone.
The type locality — Ribeirão das Posses, municipality of São Roque de Minas — is a small, cool, well-oxygenated stream associated with marginal vegetation. The collection notes indicate the fish were found in association with riparian plant matter. No water-chemistry measurements are recorded in the cache for this locality. As a rheophilic loricariid of this body size, H. alberti likely occupies shallow, swift-current microhabitats on rocks, submerged roots, and leaf litter, in the manner of other small hypoptopomatines.
Feeding
Hisonotus alberti is a herbivore-detritivore by guild, consistent with all members of Hypoptopomatinae. The suckermouth and associated dentition are adapted for rasping periphyton — the biofilm of diatoms, green algae, cyanobacteria, and associated organic detritus — from hard surfaces such as rocks, submerged roots, and woody debris.
No aquarium feeding observations are on record, but the biology of close relatives allows a reasonable inference: algae wafers, spirulina-based foods, and blanched vegetables are likely to be accepted. The trophic level estimate for H. alberti from FishBase is 2.3, indicating a diet positioned near the base of the food chain and dominated by primary producers and fine detritus.
Mating
No information on courtship or mating behaviour has been published for Hisonotus alberti, and the species does not appear to have been kept or bred in captivity. General loricariid biology suggests males of small hypoptopomatines establish territories around preferred micro-refuges and may display odontode development during the breeding season, but this has not been documented for this species specifically.
Breeding
No breeding data are available for Hisonotus alberti. Given its rarity in the aquarium trade — effectively absent — no captive breeding accounts exist. The reproductive biology of the genus Hisonotus broadly follows the general loricariid pattern of adhesive egg-laying, likely with substrate attachment in sheltered microhabitats, but details specific to H. alberti await field or captive study.
In the aquarium
Hisonotus alberti does not appear in the ornamental fish trade and is unlikely to be encountered outside specialist research collections. Its small size (under 1.5 in SL) and origin in cool, fast-flowing upland streams would, in principle, make it suitable for a small biotope aquarium replicating cerrado headwater conditions — good flow, high oxygenation, smooth rock and root structure, minimal substrate depth, and soft to moderately hard water appropriate to the upper Paraná basin.
In the absence of any husbandry records, guidance beyond these habitat inferences would be speculative. Anyone acquiring specimens — which would almost certainly mean wild-caught research material rather than trade fish — should prioritise replicating the cool, well-oxygenated conditions of the type locality.
Conservation
The IUCN Red List assessed Hisonotus alberti as Least Concern (LC) in November 2020. The assessment reflects the species' presence in two separate drainage systems (upper Paraná and São Francisco) and the absence of evidence for major population decline at the time of evaluation.
Nevertheless, the small headwater streams of Minas Gerais that this fish inhabits are subject to ongoing pressure from agricultural expansion, deforestation of riparian buffers, cattle access to stream banks, and water abstraction for irrigation — threats that are well-documented across the Brazilian cerrado. Being a stream-bottom microendemic with no apparent trade presence, H. alberti receives no protection through hobbyist breeding programmes and depends entirely on the integrity of its native catchments.