Taxonomy & naming
Parotocinclus muriaensis was described by Markus F. W. Gauger and Paulo A. Buckup in 2005, in the paper "Two new species of Hypoptopomatinae from the rio Paraíba do Sul basin, with comments on the monophyly of Parotocinclus and the Otothyrini (Siluriformes: Loricariidae)," published in Neotropical Ichthyology 3(4): 509–518. The Catalog of Fishes (Eschmeyer, CAS) lists it as valid in the genus Parotocinclus (species id 69124).
The describing paper is notable for explicitly questioning the monophyly of Parotocinclus — a recurring theme in the taxonomy of these dwarf suckermouths — and for discussing the placement of the species within the tribe Otothyrini of the subfamily Hypoptopomatinae. The specific epithet honours the Rio Muriaé, a tributary of the Paraíba do Sul where the species occurs.
Morphology
Parotocinclus muriaensis is a very small loricariid, reaching about 1 in standard length. It has the typical hypoptopomatine build: a body armoured with longitudinal rows of bony plates and a ventral suckermouth adapted for clinging and grazing.
The original description by Gauger and Buckup provides the diagnostic morphology distinguishing it from congeners, but those detailed characters were not reproduced in the source consulted here. To avoid fabrication, no specific meristic or coloration details are asserted beyond the maximum size.
Habitat
The species is restricted to the Rio Paraíba do Sul basin in southeastern Brazil, including the Rio Muriaé drainage for which it is named. It is characterised as a freshwater, demersal, tropical fish — bottom-dwelling, in warm inland waters.
No detailed habitat parameters (water chemistry, current, substrate, or seasonality) were available in the source consulted. Dwarf suckermouths of this group are generally associated with flowing, well-oxygenated streams where they cling to rocks and submerged structure, but site-specific data for this species were not on hand.
Feeding
Parotocinclus muriaensis has an estimated trophic level of 2.4, indicating the herbivore/detritivore feeding mode characteristic of the genus. It grazes aufwuchs — the algal and microbial film, together with fine detritus, that coats submerged surfaces — rasping it free with the ventral mouth.
It is not a wood-eater. No aquarium-specific feeding observations were available for this species.
Mating
No data on courtship or mating behaviour have been published for Parotocinclus muriaensis. The species is known essentially from its type material and has not been the subject of behavioural study in the source consulted.
Breeding
No breeding data are available for Parotocinclus muriaensis. There are no documented spawning reports, clutch sizes, or descriptions of parental care for this species. Small hypoptopomatines as a group are typically egg-scatterers depositing adhesive eggs on hard surfaces and vegetation, but this has not been confirmed for the present species.
In the aquarium
Husbandry data for Parotocinclus muriaensis are effectively nonexistent; the species is not part of the ornamental trade and is undocumented as an aquarium fish. No species-specific tank, water-parameter, or compatibility guidance can be given without inventing it.
General expectations for the group — mature, oxygen-rich water with established biofilm and peaceful tankmates — may apply by analogy, but these are not tested recommendations for this particular species.
Conservation
The IUCN Red List lists Parotocinclus muriaensis as Data Deficient, in an assessment dated 7 November 2018. The Data Deficient category means there is insufficient information on the species' distribution and population to make a reliable assessment of its extinction risk.
As a narrowly distributed endemic of the Rio Paraíba do Sul basin — a heavily populated and industrialised drainage in southeastern Brazil — the species could be exposed to habitat pressures, but no specific threats were detailed in the source consulted, and its true status remains unresolved.