Taxonomy & naming
Epactionotus itaimbezinho was described by Reis and Schaefer in 1998, within the subfamily Hypoptopomatinae — the dwarf suckermouth catfishes related to Otocinclus. The species is recognised as valid in FishBase.
The specific epithet refers to the Itaimbezinho canyon, a dramatic feature of the Aparados da Serra region on the Rio Grande do Sul–Santa Catarina border, near the coastal drainages the fish inhabits.
Morphology
Epactionotus itaimbezinho is a small fish, reaching about 1.5 in standard length. It has the armoured, compact body and ventral suckermouth characteristic of the Hypoptopomatinae, well suited to clinging onto surfaces in flowing water.
The diagnostic features distinguishing it from congeneric Epactionotus species are set out in the 1998 description; further morphological detail is not summarised in the sources reviewed here. No data on sexual dimorphism has been published in the references consulted.
Habitat
The species is endemic to the Mampituba River basin, a coastal drainage spanning the Rio Grande do Sul and Santa Catarina states of southern Brazil. It is a freshwater, benthopelagic, tropical fish.
These coastal streams of the Atlantic-slope region run clear over rocky and sandy beds; however, fine-scale habitat data — substrate preference, water chemistry, and current — has not been published for this species in the sources available here.
Feeding
No diet study has been published for Epactionotus itaimbezinho in the sources consulted. Dwarf Hypoptopomatinae are characteristically aufwuchs grazers, rasping algae and biofilm from rocks, wood, and plant surfaces, and this feeding mode can reasonably be expected — but it has not been confirmed for the species.
Mating
No information on courtship or mating behaviour in E. itaimbezinho has been published in the references reviewed here.
Breeding
No breeding accounts exist for Epactionotus itaimbezinho in the sources consulted, and there are no documented records of aquarium reproduction. Its reproductive biology remains unstudied in the available literature.
In the aquarium
Epactionotus itaimbezinho is rarely if ever seen in the aquarium trade, and no dedicated husbandry accounts exist in the sources reviewed here. By analogy with related dwarf Hypoptopomatinae from cool, clear coastal streams, it would likely require well-oxygenated water, moderate current, surfaces for grazing biofilm, and stable, not-too-warm tropical temperatures — but no species-specific care data can be offered without published guidance.
Conservation
The IUCN Red List assessed Epactionotus itaimbezinho as Least Concern in 2018. Despite its restricted endemic range in the Mampituba basin, the assessment did not identify threats sufficient to warrant a higher category. As with other narrow-range coastal endemics, localized habitat alteration in its single drainage would be the principal conservation concern.