Taxonomy & naming
Harttiella crassicauda was originally described by Marinus Boeseman in 1953 as Harttia crassicauda, in Zoologische Mededelingen (Leiden) volume 32, number 1, page 10, from material collected in a creek in the Nassau Mountains of Suriname. The species was later transferred to the genus Harttiella, of which it is the type species. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid combination Harttiella crassicauda (Boeseman, 1953), with the original combination Harttia crassicauda treated as a synonym — hence the parentheses around the authority, signalling the generic reassignment.
The species sits within the subfamily Loricariinae, the whiptail catfishes, a group characterised by elongate, depressed bodies and a long, slender caudal peduncle. Harttiella is a small genus of miniature loricariines associated with upland streams of the Guiana Shield.
Morphology
Harttiella crassicauda is a diminutive whiptail, reaching about 2 in standard length (SL). The body follows the typical loricariine plan: elongate and dorsoventrally flattened, sheathed in rows of bony scutes, with a slender caudal peduncle — the specific epithet crassicauda ("thick-tailed") refers to the relatively stout tail region.
Sexual dimorphism is expressed in the odontodes: males develop enlarged odontodes on the pectoral fins, a feature common among breeding male loricariids. Detailed colour and meristic data beyond the type description are sparse in the accessible literature.
Habitat
The species is restricted to small, clear forest creeks in the Nassau Mountains, within the Marowijne (Maroni) River basin of eastern Suriname. It was discovered in a small forest creek featuring cascades and a sandy-rocky bottom — a fast-flowing, well-oxygenated upland headwater environment typical of the Guiana Shield plateaus.
This is freshwater, tropical habitat at elevation on the Nassau plateau. The range is highly restricted and the populations are isolated within these upland creeks. Detailed water-chemistry measurements (temperature, pH, hardness) for the type locality are not published in the accessible sources.
Feeding
No detailed feeding study has been published for Harttiella crassicauda. As a small loricariine of fast, clear upland creeks, it is presumed to graze on the biofilm — algae, diatoms, and associated micro-detritus — coating rocks and submerged surfaces, consistent with the feeding ecology of related whiptail catfishes. Specific dietary data for this species remain unpublished.
Mating
No courtship or mating behaviour has been documented for Harttiella crassicauda. The presence of enlarged pectoral-fin odontodes in males suggests these structures play a role in male-male competition or breeding-territory defence, as in many other loricariids, but this has not been observed or described for the species itself.
Breeding
No breeding report exists for Harttiella crassicauda. Its reproductive mode, clutch size, spawning site, and any parental care are unknown. Given the restricted, upland-creek habitat and the conservation concern surrounding the species, no captive breeding data are available either.
In the aquarium
Harttiella crassicauda is not a hobby species. It is a small, range-restricted, Endangered fish of remote Surinamese upland creeks, and there is no established aquarium trade or husbandry record for it. Any specimen in collections would be of scientific rather than ornamental interest. As a fish adapted to cool, clear, fast-flowing, highly oxygenated headwaters, it would in any case be demanding to maintain; the appropriate posture toward this species is conservation and habitat protection rather than collection.
Conservation
The IUCN Red List assessed Harttiella crassicauda as Endangered (EN) in 2020. The listing reflects the species' extremely restricted range — confined to small, isolated upland creeks on the Nassau plateau within the Marowijne basin of Suriname — and the vulnerability of that fragile habitat to disturbance.
The principal threat is mining activity in the Nassau Mountains region: the plateau holds bauxite and gold deposits, and extraction, road-building, and the associated sedimentation, deforestation, and altered hydrology directly imperil the narrow forest-creek environment on which the species depends. With a tiny geographic footprint and no buffer populations elsewhere, even localised habitat degradation could affect a large fraction of the total population, underscoring the Endangered assessment.