Taxonomy & naming
Harttia tuna was described by Raphaël Covain and Sonia Fisch-Muller in 2012 and is recognised as a valid species. It belongs to the subfamily Loricariinae within the family Loricariidae.
The genus name Harttia honours the geologist and naturalist Charles Frederick Hartt (1840–1878). The specific epithet tuna derives from the Amerindian Trio-Wayana word for 'river' or 'water'; according to the descriptive notes, it was chosen in reference to the morphologically similar Harttia fluminensis, whose own name (from Latin flumen, a river) carries the same watery meaning.
Detailed phylogenetic placement of H. tuna within Harttia is not summarised in the sources available here.
Morphology
Harttia tuna reaches a maximum recorded size of about 7 in standard length. Like other members of the genus it shows the elongate, dorsoventrally flattened body and long slender caudal peduncle characteristic of the whiptail loricariins, with a ventral suckermouth and the bony dermal armour of the family.
The species was noted as morphologically similar to Harttia fluminensis, which is reflected in its naming. Beyond these points, a full colour and meristic description and any account of sexual dimorphism are not available in the sources at hand.
Habitat
Harttia tuna is a freshwater, demersal, tropical species native to South America, recorded from the upper Paru de Oeste River in Brazil, within the Guiana Shield drainage. More specific habitat data — substrate, current, seasonal conditions, and measured water chemistry — are not documented in the sources available here.
Feeding
No species-specific diet study for Harttia tuna is available in the sources at hand. Loricariins of this body form are generally substrate grazers feeding on biofilm (aufwuchs), algae, and associated micro-invertebrates and detritus, but a precise diet for this species should not be assumed beyond that general pattern.
Mating
No account of courtship or mating behaviour in Harttia tuna is published in the sources available here.
Breeding
No breeding data for Harttia tuna are documented in the sources at hand. While many Loricariinae are substrate spawners with paternal egg care, no spawning observations specific to this species are available, and none should be inferred.
In the aquarium
Harttia tuna is a Guiana Shield species not established in the ornamental trade, and no aquarium husbandry record exists in the sources available here. No captive-care claims specific to this species can be substantiated.
Conservation
The IUCN Red List assessed Harttia tuna as Least Concern in 2020. No species-specific threat detail beyond this listing is summarised in the sources available here.