Taxonomy & naming
Epactionotus yasi was described by Almirón, Azpelicueta and Casciotta in 2004, from material collected in the upper Río Paraná / Iguazú region of Misiones Province, northeastern Argentina. It is placed in the subfamily Hypoptopomatinae of the family Loricariidae, the group of small suckermouth armoured catfishes that includes Otocinclus and related dwarf genera.
The genus Epactionotus is a southern South American radiation of these dwarf loricariids, associated with the subtropical drainages of the Río Paraná and Río Uruguay systems and adjacent coastal rivers. Beyond the original description, little additional taxonomic literature has been published on E. yasi specifically.
Morphology
Epactionotus yasi is a small loricariid with the dorsoventrally flattened, armour-plated body typical of the Hypoptopomatinae, and a ventral suckermouth used to adhere to substrate. A precise published maximum size for the species is not available in the sources consulted, though members of the genus are dwarf catfishes of a few centimetres.
No detailed morphometric or coloration summary beyond the original description is available here, and no data on sexual dimorphism in this species have been published in the sources reviewed.
Habitat
The species occurs in the freshwater streams of the upper Río Paraná and Iguazú region of Misiones, Argentina — a subtropical area of clear, flowing watercourses. FishBase classifies it as a freshwater, benthopelagic, tropical species.
Detailed water-chemistry, depth and seasonal data for the type locality are not published in the sources consulted. As with other Hypoptopomatinae, the species is expected to favour well-oxygenated water and firm surfaces (rock, wood, submerged vegetation) to which it can cling, but specific microhabitat records are not available.
Feeding
No diet data have been published for Epactionotus yasi in the sources consulted. Hypoptopomatine loricariids are generally aufwuchs grazers, rasping algae, biofilm and associated micro-organisms from submerged surfaces, but the specific feeding ecology of this species is not documented here.
Mating
No data on courtship or mating behaviour have been published for this species in the sources consulted.
Breeding
No breeding data — reproductive mode, clutch size, or parental care — have been published for Epactionotus yasi in the sources consulted.
In the aquarium
Epactionotus yasi is not a commonly traded aquarium fish, and no established husbandry record is available in the sources consulted. By analogy with other small Hypoptopomatinae, it would be expected to require clean, well-oxygenated water, gentle to moderate flow, and surfaces grazed with biofilm and algae; however, no species-specific aquarium guidance can be given without inventing detail.
Conservation
The species has not been formally assessed on the IUCN Red List (Not Evaluated). It is known from a restricted area of northeastern Argentina, which can make narrow-range stream species sensitive to local habitat change, but no formal conservation assessment or population data are available in the sources consulted.