Taxonomy & naming
Harttia longipinna was described in 2001 by Francisco Langeani, Osvaldo T. Oyakawa, and Juan I. Montoya-Burgos. The Catalog of Fishes (Eschmeyer, CAS) recognises it as a valid species (genus Harttia, species longipinna), and FishBase follows the same valid combination.
The genus Harttia belongs to the subfamily Loricariinae, the depressed-bodied 'whiptail' loricariids, and the species appears in Ferraris's 2003 checklist of the freshwater fishes of South and Central America (in Reis, Kullander & Ferraris, eds.).
The epithet longipinna combines the Latin longus ('long') and pinna ('fin'), referring to a long fin — typically read as the elongate fin development noted in the species; this is offered on the Latin roots rather than from a quoted etymology in the sources available.
Morphology
Harttia longipinna is among the larger species of its genus, reaching a maximum recorded size of about 6 in standard length (SL), with a maximum published weight of roughly 38.8 g — substantially larger than the ~3.5 in congeners of southeastern Brazil. It shows the genus-typical loricariin build: a flattened, depressed body, a long tapering caudal peduncle, and a ventral suckermouth disc, the epithet pointing to notably elongate fin development.
Further meristic detail, colour pattern, and any sexual dimorphism are set out in the 2001 description; those particulars are not summarised in the sources available here, so no additional morphological claims are made.
Habitat
The species occurs in the upper São Francisco River basin in Brazil. It is a tropical freshwater fish and demersal, living on or near the bottom consistent with the substrate-grazing biology of the genus.
No site-specific water chemistry — temperature, pH, hardness, or depth — is reported for this species in the sources at hand, so none is asserted. The genus generally favours clear, flowing rivers and streams with firm substrate.
Feeding
Harttia longipinna is a benthic grazer, with an estimated trophic level of about 2.5 (FishBase), indicating a diet dominated by low-trophic foods — the algal biofilm (aufwuchs), micro-invertebrates, and detritus rasped from rocks and submerged surfaces with the ventral suckermouth.
No species-specific diet study is available in the sources here; the dietary picture rests on the genus's grazing habit and the estimated trophic level.
Mating
No mating or courtship behaviour has been published for Harttia longipinna in the sources available here. Several congeners are lithophilous rock-spawners with paternal egg care, but no such observation is recorded for this species, so none is claimed.
Breeding
No breeding data — spawning site, clutch size, incubation, or parental care — have been published for Harttia longipinna in the sources at hand, and there is no documented captive spawning. Reproductive specifics for the species remain undocumented here.
In the aquarium
Harttia longipinna is not part of the ornamental trade and has no established husbandry record. As a relatively large flowing-water loricariin, its broad needs would resemble those of other whiptail Harttia — clean, well-oxygenated current over firm grazing surfaces, with space appropriate to its larger size — but because no documented keeping experience exists in the sources here, no specific parameters or stocking advice are offered.
Conservation
The IUCN Red List assessed Harttia longipinna as Least Concern (LC) in 2022. It was not considered to face threats sufficient for a higher category at assessment. As with other fishes restricted to the upper São Francisco system, habitat alteration from damming, water abstraction, and pollution remains a background concern, but no specific population decline is documented in the sources here.