Taxonomy & naming
Chaetostoma carrioni was formally described by Norman in 1935 in the Annals and Magazine of Natural History (Series 10, volume 15, number 90, page 628). The original description placed the species in Lipopterichthys as Lipopterichthys carrioni — a genus that is now treated as a junior synonym of Chaetostoma. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid combination Chaetostoma carrioni (Norman, 1935), with Lipopterichthys carrioni cited as the basionym.
The transfer from Lipopterichthys to Chaetostoma reflects ongoing revisions of the Chaetostomini tribe of subfamily Hypostominae. Chaetostoma is diagnosed by the presence of interopercular odontodes, the absence of abdominal plates, and the absence of snout-edge plates — characters that collectively separate it from the superficially similar Ancistrus, which bears fleshy tentacles on the snout. Males of Chaetostoma species also carry disproportionately large pelvic fins, which distinguish them from females.
No valid common name is registered for this species, and it has not been assigned an L- or LDA-number, reflecting its minimal representation in the ornamental trade.
Morphology
Adults reach a maximum recorded length of 3 in standard length (SL), making Chaetostoma carrioni among the smaller members of a generally compact genus. The body is encased in the typical loricariid armour of interlocking bony scutes, robust enough to resist abrasion against the boulder substrates this genus favours.
The genus Chaetostoma is distinguished by interopercular odontodes — stiff, bristle-like projections at the cheek margin — which are more developed in males. The ventrally positioned, disc-like mouth is adapted for suction-attachment and biofilm grazing rather than deep wood-rasping. The pelvic fins are notably enlarged in males relative to females — a consistent feature across Chaetostoma that assists in identification of sex.
Photographic documentation is limited; lateral, lateral, and dorsal views are on file at PlanetCatfish. Detailed colouration data specific to C. carrioni are sparse in the available literature, and no additional morphometric data beyond the 3 in SL maximum are recorded in accessible sources.
Habitat
Chaetostoma carrioni is known from the Zamora and Santiago river drainages, tributaries of the upper Marañón system within the greater Amazon basin, in eastern Ecuador. The type locality is the Río Zamora near Loja, Goiás State, at elevations typical of Andean foothill rivers. PlanetCatfish records the distribution as encompassing the upper Amazon, Marañón, upper Marañón, Santiago, and Zamora river systems.
The genus Chaetostoma is strongly rheophilic — adapted to fast-flowing, well-oxygenated water over rocky and boulder-strewn substrates. Individuals cling to current-exposed rock faces and use their suctorial mouths to graze periphyton and biofilm without being swept downstream. This rheophilic lifestyle implies cool, highly oxygenated, clear to lightly turbid water at Andean foothill elevations, though specific physical and chemical measurements for C. carrioni's habitat are not recorded in the available sources.
Microhabitat preference, as recorded for Chaetostoma species generally, centres on well-rounded stones providing both feeding surface and sheltering cavities in areas of moderate to swift current.
Feeding
Chaetostoma carrioni is a periphyton and biofilm grazer. The ventrally positioned, suctorial mouth is morphologically suited for scraping algae, diatoms, and associated organic material from hard rock and boulder surfaces in fast-flowing water. This feeding mode is shared broadly across the genus and distinguishes Chaetostoma from the xylophagous (wood-eating) Panaqolus and Panaque or the more herbivorous Pterygoplichthys.
In the aquarium, Chaetostoma species are typically maintained on a diet of algae wafers, spirulina-based foods, blanched vegetables such as courgette (zucchini), and cucumber, supplemented by natural algae growth on aquarium surfaces. The genus is generally considered safe with plants. Provision of smooth rocks with established algae biofilm closely replicates natural foraging conditions and is recommended for long-term maintenance.
No captive feeding observations specific to C. carrioni are documented, and the species has no registered keepers on PlanetCatfish.
Mating
Specific courtship observations for Chaetostoma carrioni are absent from the available literature. The general loricariid pattern in cave-spawning genera includes male site defence, with males selecting and guarding shallow cavities under flat objects or within rock crevices before and during spawning.
For Chaetostoma species, PlanetCatfish notes that spawning occurs in shallow, fast-flowing water on the underside of flat objects, with the male positioned upside-down to guard the adhesive egg clutch. Males within the genus are identifiable by their larger, broader head profile, proportionally more slender body when viewed ventrally, and disproportionately large pelvic fins — features that become more pronounced in mature, conditioned individuals.
No captive breeding reports or aquarium courtship observations are on record for this species.
Breeding
No captive breeding of Chaetostoma carrioni has been documented in accessible records. The species is not represented among registered keepers on PlanetCatfish, and no spawning accounts appear in the available literature.
Based on the biology of Chaetostoma species generally, the reproductive mode is expected to involve cave or cavity spawning with adhesive eggs deposited on the underside of flat objects in areas of current. Paternal brood care, with the male guarding the clutch and fanning eggs, is the pattern typical of the broader loricariid tribe. Clutch size data are not available for this species.
Given the rheophilic nature of the genus and its Andean foothill origin, replication of cool, fast, well-oxygenated water conditions with appropriate shelter objects would be the logical starting point for any attempted captive breeding.
In the aquarium
Chaetostoma carrioni is rarely encountered in the hobby and has no documented presence in the ornamental trade. No captive keeping records exist for this species on PlanetCatfish, and it has not been assigned an L-number.
Its small adult size (to 3 in SL) and rheophilic ecology suggest it would require a well-oxygenated aquarium with strong, directed water flow, smooth boulders and pebbles, and a cool to moderate temperature regime reflecting its Andean foothill origin. Algae-covered rockwork and a varied algae-based diet would be appropriate.
For aquarists interested in the Chaetostoma genus more broadly, species from better-represented populations in Colombia and Venezuela are more reliably sourced; C. carrioni's Data Deficient IUCN status and limited distribution counsel caution regarding wild collection, and its near-absence from trade means captive-bred specimens are not currently available.
Conservation
The IUCN Red List assessed Chaetostoma carrioni as Data Deficient in an assessment dated 8 October 2014. The listing reflects the limited population and ecological data available at the time of assessment rather than an absence of threat. The species' range is restricted to the Zamora and Santiago drainages of the upper Marañón system in eastern Ecuador — a geographically limited distribution that in principle raises concern about resilience to habitat change.
Eastern Ecuador's Andean foothill rivers face pressures from deforestation, agricultural runoff, and mining activity affecting water quality and sediment loads — factors that are particularly detrimental to rheophilic species adapted to clean, clear, fast-flowing rocky habitats. Without improved survey data, the species cannot be categorised more precisely on the IUCN scale. Targeted field assessment of population status and habitat quality in the Zamora and Santiago drainages would be necessary to support a future uplift or downlisting.