Taxonomy & naming
Paraloricaria agastor was described by the Dutch ichthyologist Isaäc J. H. Isbrücker in 1979. The species is recognised as valid by the Catalog of Fishes (Eschmeyer, CAS) and by FishBase as Paraloricaria agastor Isbrücker, 1979.
The genus Paraloricaria sits within the subfamily Loricariinae, the whiptail catfishes, characterised by their elongate, depressed bodies and long, slender caudal peduncles. The principal modern reference for the species is Ferraris (2003), the Checklist of the Freshwater Fishes of South and Central America. No L-number or hobby code is associated with this fish.
Morphology
Paraloricaria agastor reaches about 4.5 in standard length (SL) in the largest recorded specimen. In keeping with the subfamily Loricariinae, it has an elongate, dorsoventrally flattened body armoured with bony plates and tapering to a long, thin caudal region.
Detailed meristic and morphometric data are confined to the original description by Isbrücker (1979); no colour-in-life description or account of sexual dimorphism is reproduced in the sources consulted.
Habitat
FishBase classifies Paraloricaria agastor as a freshwater, demersal, tropical species. It is recorded from the Paraguay River basin (the source of the type material) and is also reported from the Paraná and Uruguay River basins — placing it within the broader La Plata drainage of central South America.
No specific field data on substrate, current, or water chemistry has been published for the species; the FishBase resilience estimate is given as high. Beyond the basin-level distribution, the microhabitat of this whiptail is undescribed.
Feeding
No direct diet study has been published for Paraloricaria agastor. FishBase provides only a model-based trophic-level estimate of 2.6, indicating a position low in the food web consistent with the detritus- and biofilm-feeding habits typical of whiptail loricariines. The actual stomach contents and feeding ecology of this species remain undocumented.
Mating
No data has been published on courtship or mating behaviour in Paraloricaria agastor.
Breeding
No data has been published on the reproductive biology of Paraloricaria agastor. Many Loricariinae are lip- or fin-brooders that carry their eggs, but no spawning observations exist for this species, and its mode of reproduction has not been described.
In the aquarium
Paraloricaria agastor is not a species of the ornamental trade, and no aquarium husbandry information has been published for it. Care expectations could only be inferred from better-known sand-dwelling whiptail catfishes, and such inference is not offered here as documented guidance for this species.
Conservation
The IUCN Red List assessed Paraloricaria agastor as Least Concern (LC), with the assessment dated 3 February 2021. The wide distribution across the Paraguay, Paraná, and Uruguay basins of the La Plata system underlies this classification, and the species is not listed under CITES or CMS.