Taxonomy & naming
Farlowella altocorpus was formally described by Michael E. Retzer in 2006 in Zootaxa (issue 1282, pp. 59–68), from specimens collected in the Río Coroico, a tributary of the Río Beni in Bolivia. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid name Farlowella altocorpus Retzer, 2006. The original description was based on six specimens, and the type locality is restricted to the Río Coroico drainage within the Beni basin.
The genus Farlowella Eigenmann & Eigenmann, 1889 is an assemblage of elongate, twig-mimicking loricariids placed in the subfamily Loricariinae. Species in the genus are notoriously difficult to distinguish, being among the most morphologically conservative in the family; new species continue to be described as material from undersampled Andean-foothill drainages is examined. Retzer placed F. altocorpus in the Farlowella nattereri species group and distinguished it from congeners primarily by the combination of possessing five rows of anterior lateral plates and a relatively deep body — characters reflected in the species epithet.
No synonym or additional combination has been applied since the original description. FishBase assigns the species its own entry (species ID 63504), confirming its acceptance as a valid taxon.
Morphology
Farlowella altocorpus reaches 6.5 in standard length (SL) — a size within the mid-range of the genus. The body is extremely elongate and rod-like in the typical Farlowella fashion, with the rostrum projecting as a pointed snout that accentuates the twig-like impression. The defining diagnostic character is the relatively deep body when compared to most other species in the genus: the species epithet derives directly from this feature (Latin altus, deep or high; corpus, body).
The lateral plate formula — specifically the five rows of anterior lateral plates — is the other key osteological diagnostic used in the original description. Like all Farlowella, the fish is covered in rows of keeled scutes, with the dorsal and ventral keels contributing to the angular cross-section that, combined with slender proportions and cryptic colouration, makes the animal virtually invisible when resting motionless against woody debris or reed stems.
Colouration details for live specimens are not documented in available summary sources. Congeners are typically brown to tan with darker mottling, blending with submerged wood and vegetation. Sexual dimorphism in Farlowella is usually expressed through the presence of stiff odontodes on the snout of adult males, which females lack — a pattern described across several congeners and likely applicable here, though not confirmed specifically for F. altocorpus.
Habitat
The type and only known locality for Farlowella altocorpus is the Río Coroico, a tributary of the Río Beni draining the eastern Andes of Bolivia. The Beni basin ultimately discharges into the Madeira River, the largest right-bank tributary of the Amazon. The Coroico descends steeply from the Yungas cloud-forest zone of the Bolivian Andes — a region of exceptional biodiversity and high endemism — into the Amazonian lowlands.
No published water-chemistry data are available for F. altocorpus at its type locality. In the broader Yungas drainage context, rivers emerging from the Andean slopes carry moderate sediment loads and vary considerably in temperature and chemistry depending on altitude and season. Farlowella in general associate with slow to moderately flowing stretches, resting on submerged vegetation, reed stems, wood, and debris piles where their body shape provides cryptic concealment.
The very limited number of known specimens (six from the original description) means the full extent of the species' range within the Beni basin is unknown. It may occur beyond the Coroico drainage, or it may be genuinely restricted — the data do not allow a determination.
Feeding
Farlowella species are grazers of periphyton and fine organic matter, using a ventral suctorial mouth equipped with small teeth to scrape algal films, diatoms, and biofilm from hard surfaces. The extremely elongate body allows the fish to rest horizontally along stems and branches, rasping their entire length without repositioning. In the genus broadly, gut contents studies have recovered diatoms, green algae, detritus, and fine plant material.
For F. altocorpus specifically, no dietary study has been conducted. In aquaria, congeners do well on algae wafers, blanched greens (courgette, cucumber, spinach), and the biofilm that accumulates on mature driftwood and broad-leaved plants such as Anubias. Supplemental feeding of soft vegetables is important in tanks where algal growth alone is insufficient to sustain the grazing requirements of these fish.
Mating
Courtship and mating behaviour have not been described for Farlowella altocorpus. In related and better-known Farlowella species maintained in captivity, males with well-developed snout odontodes engage in mild territorial behaviour around preferred spawning sites, which are typically broad, smooth surfaces — large plant leaves, the glass of the aquarium, or flat pieces of wood. Males may nudge or prod females during courtship.
Whether F. altocorpus has entered captive care at all is not documented in accessible literature. Breeding data for this species are absent.
Breeding
No breeding records exist for Farlowella altocorpus. Congeners such as Farlowella acus have been bred in captivity and provide the closest available reference for the genus. In those accounts, eggs are deposited in a flattened adhesive cluster on a smooth vertical surface — often the aquarium glass or a broad plant leaf — and the male guards and fans the egg mass until hatching. Clutch sizes in congeners range from a few dozen to over a hundred eggs. Larvae are long and thin from hatching, reflecting the adult body plan.
Given that F. altocorpus is not established in the hobby and has been described from only six wild specimens, captive breeding data remain entirely absent. Extrapolation from congener accounts is the limit of what can responsibly be offered.
In the aquarium
Farlowella altocorpus is not currently available in the ornamental trade and has no documented aquarium history. Any husbandry notes must be drawn from the genus-level knowledge base accumulated around better-known species such as F. acus and F. gracilis.
Twig catfishes generally require planted or decorated aquaria with broad-leaved plants, driftwood, and stable, well-oxygenated water. They are sensitive to water quality degradation, particularly elevated nitrates and ammonia, and should not be kept in newly established tanks. Water conditions consistent with a Bolivian Yungas-foothill tributary — warm (75–81 °F is likely appropriate, though unconfirmed for this species), soft to moderately hard, near-neutral — would provide a reasonable starting point if material were ever to become available. Quiet, non-turbulent flow suits the generally sluggish movement of these ambush-resting grazers.
The species' IUCN Data Deficient status underscores the lack of information available to guide either conservation or hobbyist management.
Conservation
The IUCN Red List assessed Farlowella altocorpus as Data Deficient (DD) in 2014, reflecting that insufficient distributional and population data are available to make a meaningful threat assessment. Known only from a single river system in Bolivia and described from six specimens, the species' actual range, abundance, and population trend are entirely uncharacterised.
The Río Coroico drainage, while part of the high-biodiversity Yungas zone, is subject to increasing human pressure: road construction (notably the Yungas Road), agricultural expansion, coca cultivation, and associated erosion and sedimentation affect streams in the region. Whether these pressures affect F. altocorpus populations cannot be determined without basic survey data. The combination of single-locality knowledge and a rapidly changing landscape justifies precautionary concern, even absent a formal threatened listing.
Future ichthyological surveys of Beni-basin tributaries, particularly in the Yungas transition zone, may clarify whether F. altocorpus is genuinely rare or simply undersampled — a distinction that matters considerably for any future conservation decision.