Taxonomy & naming
Harttiella parva was described by Covain and Fisch-Muller in 2012 in their revision of the Harttiini of the Guianas (Cybium 36(1): 115–161). It is a member of subfamily Loricariinae within the armoured catfish family Loricariidae, and is recorded in FishBase under SpecCode 66586.
It is the smallest species in the genus. Its diagnosis combines this small body size with an unusually early onset of sexual dimorphism (expressed at around 1 in standard length, versus roughly 1 in in congeners), a distinctive banded caudal-fin colour pattern, and specific DNA-barcode sequences. The specific epithet derives from the Latin parvus, meaning 'small', a direct reference to its size.
Morphology
Harttiella parva is the smallest member of its genus, with type material reaching about 1 in standard length. It has the elongated, armour-plated body characteristic of the genus. Among its diagnostic traits are its small overall size, a distinct banded colour pattern on the caudal fin, and barcode characters. Recorded fin-ray counts are seven dorsal soft rays, one anal spine, and five anal soft rays.
Sexual dimorphism appears at a notably small body size in this species — around 1 in standard length, earlier than the roughly 1 in seen in related Harttiella — though the consulted sources do not detail the specific external differences between the sexes.
Habitat
Harttiella parva is known only from its type locality: a small forest creek in the Atachi Bakka Mountains of French Guiana. It is a freshwater, demersal fish of tropical upland streams, living on the bottom of flowing forest waters. Like several of its congeners, its entire known range is a single stream.
No published water-chemistry measurements (temperature, pH, hardness) for the type creek are available in the consulted sources.
Feeding
No direct dietary study of Harttiella parva has been published. FishBase assigns a modelled trophic level of about 2.9, consistent with the general loricariine pattern of grazing biofilm, attached algae, and associated micro-organisms and detritus from submerged surfaces in forest streams. Specific gut-content or feeding data for the species are not available.
Mating
No data on the courtship or mating behaviour of Harttiella parva has been published. The only reproductive-biology detail recorded is that sexual dimorphism becomes expressed at a small size, around 1 in standard length.
Breeding
No data on the reproduction, spawning mode, clutch size, or parental care of Harttiella parva has been published.
In the aquarium
Harttiella parva is not an aquarium fish. It is a Critically Endangered, single-locality endemic with no presence in the ornamental trade and no documented husbandry, so there are no captive-care guidelines to offer. The species belongs to the domain of field study and conservation rather than the hobby.
Conservation
The IUCN Red List assessed Harttiella parva as Critically Endangered (CR) under criteria B2ab(iii), with the assessment dated 14 January 2021. The listing reflects an extremely restricted range — a single forest creek in the Atachi Bakka Mountains of French Guiana — together with a projected continuing decline in habitat quality.
With its whole known population confined to one upland stream, H. parva is acutely exposed to any localised disturbance: deforestation, sedimentation, water abstraction, or pollution affecting that single catchment could threaten the species' survival. Its tiny body size and single-creek distribution place it among the most vulnerable loricariids of the Guiana Shield.