Taxonomy & naming
Sturisomatichthys caquetae was described by Henry Weed Fowler of the Philadelphia Academy of Natural Sciences in 1945, with the original description traced via the Catalog of Fishes to the Proceedings of the Academy of Natural Sciences of Philadelphia volume 97. The species was placed in Sturisoma on the basis of body plan and morphological characters shared with the group. The Catalog of Fishes (Eschmeyer, CAS) recognises the current valid combination Sturisomatichthys caquetae (Fowler, 1945).
The genus Sturisoma belongs to the subfamily Loricariinae, the whiptail and twig catfishes of South and Central America. Phylogenetic placement within Loricariinae was addressed by Covain et al. (2015), whose molecular work on the subfamily provides the most comprehensive modern treatment of loricariine relationships (FishBase reference 110098).
The genus name combines the Latin-derived sturio ('sturgeon', in use since the 16th century) with the Greek soma ('body') — a reference to the armoured, elongate, somewhat sturgeon-like form of these catfishes. The species epithet caquetae is a Latinised form of Caquetá, the Colombian river system from which the type specimens were collected.
This fish was long listed as Sturisoma caquetae; Eschmeyer's Catalog of Fishes places the species in Sturisomatichthys, and the current combination Sturisomatichthys caquetae is followed here.
Morphology
FishBase records a maximum length of approximately 7.6 in for Sturisomatichthys caquetae (reference 36389), though the measurement type is not specified on the species summary page; based on the norm for the genus, this is likely standard length. Sturisoma species are larger and more robust than Farlowella twig catfishes, though still distinctly elongate: the body tapers from a relatively broad, depressed head to a slender caudal peduncle, and the rostrum (snout extension beyond the mouth) is pronounced, giving the characteristic whiptail profile.
The body is armoured with rows of bony scutes. Coloration in the genus is typically tan to brown with darker patterning, though species-specific details for S. caquetae are not well documented in available sources. The caudal fin in Sturisoma often bears elongated filamentous extensions on the upper and lower lobes — a feature prominent in several congeners, though whether this is equally developed in S. caquetae is not confirmed by the records consulted.
Sexual dimorphism in the genus is well established: males develop conspicuous cheek bristles (odontodes along the interopercle) in breeding condition, and females become noticeably broader across the abdomen when gravid. These characters are expected in S. caquetae based on genus-level patterns.
Habitat
Sturisomatichthys caquetae is known from the Caquetá River basin of Colombia. The Caquetá (called the Japurá once it crosses into Brazil) rises in the Colombian Andes and descends through mid-elevation terrain onto the Amazonian lowland plain — a river system draining both Andean and Amazon-margin terrain. FishBase categorises the species as freshwater and demersal, with a tropical temperature regime.
No specific habitat data (pH, hardness, temperature, microhabitat type) are available for S. caquetae beyond the basin-level assignment. By analogy with other Sturisoma from Andean-Amazon drainages, the species likely favours shallow, flowing reaches with moderate current, where the fish graze on periphyton-coated hard substrates — submerged wood, smooth rocks, and root masses. The genus includes facultative air-breathers capable of supplementing gill respiration when dissolved oxygen is low (FishBase reference 126274), a useful adaptation in seasonally variable Amazonian-origin rivers.
Beyond this, reliable habitat data for S. caquetae specifically are sparse, and extrapolation from congeners must be treated cautiously.
Feeding
Sturisoma species are herbivorous periphyton grazers and biofilm scrapers, using their ventral mouths and fine rasping teeth to remove thin films of algae, diatoms, and associated microorganisms from hard surfaces. The genus is not a wood-eater in the way that Panaqolus or Panaque are; the diet centres on surface biofilm rather than lignocellulose. This feeding mode is shared across Loricariinae and is adapted to environments where periphyton communities are well-developed on submerged surfaces in flowing water.
Specific dietary observations for S. caquetae in nature or captivity are not available in the records consulted. In congeners that are established in the hobby — such as Sturisoma panamense and S. festivum — the accepted aquarium diet includes algae wafers, spirulina tablets, blanched vegetables (courgette, spinach, cucumber), and established algal growth on driftwood and glass. This general dietary framework is reasonable for S. caquetae given the shared morphology, but direct confirmation is absent.
Mating
No behavioural observations specific to Sturisomatichthys caquetae courtship are available. In the genus Sturisoma, which includes species with an established aquarium breeding record, males develop prominent cheek bristles (interopercular odontodes) in breeding condition and use these in male-to-male competition around preferred spawning sites — typically smooth vertical surfaces such as aquarium glass, broad leaves, or flat sections of wood.
Courting males in documented congeners engage in prolonged parallel positioning with the female near the chosen surface, and the female deposits eggs directly onto it. The male's role in egg attendance begins immediately after spawning. Whether these patterns hold in full for S. caquetae is unconfirmed, but the shared anatomy makes comparable behaviour plausible.
Breeding
Sturisomatichthys caquetae does not appear in the PlanetCatfish Cat-eLog, and no aquarium breeding accounts are available in the records consulted. The species is not known as an aquarium fish with any significant hobbyist history, and breeding data are accordingly absent.
Sturisoma species in general are open-substrate spawners that deposit adhesive eggs on smooth vertical surfaces — aquarium glass, the underside of broad leaves, or flat wood — with the male taking exclusive responsibility for guarding the clutch. In well-documented congeners, the male fans the eggs continuously with his pectoral and ventral fins to maintain oxygen flow, and incubation lasts approximately five to ten days at typical tropical temperatures. Fry in the genus are relatively robust compared to Farlowella, but this is based on congener data; no direct information is available for S. caquetae.
In the aquarium
Sturisomatichthys caquetae is not an established aquarium species. It does not appear in the PlanetCatfish Cat-eLog, and no hobbyist accounts of its maintenance or breeding are available in the records consulted. It is not possible to provide specific tank parameters, compatibility notes, or care recommendations based on direct experience with this species.
General Sturisoma husbandry guidance — clean, well-oxygenated water; moderate current; abundant grazing surfaces; plant-based diet — is derived from congeners and should not be applied to S. caquetae without acknowledging the gap. Any keeper acquiring this species would be working with limited precedent and would be advised to document and share observations to build the knowledge base for the taxon.
Conservation
The IUCN Red List assessed Sturisomatichthys caquetae as Data Deficient (DD) in October 2014. The assessment reflects a lack of sufficient information about the species' distribution extent, population size, and exposure to threats — not a documented finding of rarity or decline. The Caquetá basin in Colombia is subject to ongoing deforestation and agricultural expansion in its mid-elevation reaches, which increase sedimentation and alter river hydrology; how these pressures affect S. caquetae specifically is unknown.
The species is not listed on CITES appendices. Given that it is not established in the aquarium trade and lacks a hobbyist record, collection pressure is unlikely to be a significant factor at present. The Data Deficient designation signals a need for targeted field survey work in the Caquetá basin to resolve the species' status.