Taxonomy & naming
Dolichancistrus carnegiei was described by Carl H. Eigenmann in 1916 from material collected during Carnegie Museum expeditions to South America. A complementary description with an illustration of the holotype appeared in Eigenmann (1922: 79, plate 10, figure 3). Isbrücker transferred the species to Dolichancistrus in 1980 (Beaufortia 30(1):43), and the Catalog of Fishes (Eschmeyer, CAS) recognises Dolichancistrus carnegiei as the valid name. No synonyms are listed. Fisch-Muller (2003) records the species in the Check List of the Freshwater Fishes of South and Central America (CLOFFSCA) from Colombia.
Dolichancistrus belongs to the subfamily Hypostominae (tribe Ancistrini) and encompasses elongated Andean rheophilic loricariids. The type locality is the Magdalena River basin, Colombia.
Morphology
Adults reach up to 6.5 in total length (TL), making D. carnegiei the largest of the three species treated in this series and a sizeable representative of its genus. The body is elongated — as the genus name implies — with the flattened, heavily-scuted profile characteristic of rheophilic Hypostominae built for life on boulder and cobble substrate in flowing water. The ventrally positioned scraping mouth is adapted for grazing periphyton from rock surfaces.
No detailed colouration notes beyond those in the original type description are available in the literature consulted. The holotype illustration in Eigenmann (1922, plate 10 fig. 3) provides the primary morphological reference for this species.
Habitat
Dolichancistrus carnegiei is endemic to the Magdalena River basin in Colombia. The Magdalena is one of Colombia's major drainage systems, rising in the Colombian Andes and flowing northward to the Caribbean Sea. The basin encompasses a wide elevational gradient, from high Andean tributaries to lowland floodplains, with the fast-flowing montane and submontane reaches providing the hard-substrate, high-oxygen habitat typical of Dolichancistrus.
FishBase records water parameters for D. carnegiei as pH 6.0–7.0 and temperature 72–79 °F, representing the cooler, slightly acidic to neutral conditions of Andean river systems at mid-elevation. Hardness data are incomplete. The species is classified as freshwater, demersal, and tropical. The Magdalena basin is biogeographically significant as an isolated Andean drainage with a high degree of endemism among loricariids and other freshwater fishes.
Feeding
No feeding data specific to Dolichancistrus carnegiei are documented in the available literature. The scraping mouth morphology and rheophilic ecology of the genus are consistent with grazing periphyton — the community of algae, diatoms, cyanobacteria, and associated biofilm that colonises submerged rock surfaces in fast, clear Andean rivers. This is the dominant feeding mode among Andean Hypostominae of similar morphology.
No captive feeding observations are on record for this species.
Mating
No mating or courtship data are documented for Dolichancistrus carnegiei. The species has not been reported in the aquarium trade in any quantity sufficient to generate hobbyist observations. Based on the broader Andean rheophilic Hypostominae, males of related taxa are expected to be territorial around rocky spawning sites and to develop odontode elaboration during breeding condition, but nothing species-specific is recorded.
Breeding
No breeding data are available for Dolichancistrus carnegiei in the wild or captivity. The species has not been recorded as having bred in aquaria. No clutch size, incubation period, or parental care mode is documented. Any such information would require either field study in the Magdalena basin or successful captive maintenance, neither of which is currently on record.
In the aquarium
Dolichancistrus carnegiei has no documented aquarium trade or captive husbandry history. As a Magdalena endemic with a mid-elevation Andean distribution, it would likely require relatively cool, well-oxygenated, slightly acidic to neutral water (pH 6.0–7.0, around 72–79 °F) with strong current and hard substrate in any aquarium setting. At 6.5 in TL, a specimen of full size would require a tank of appropriate volume with robust filtration capable of maintaining the water quality that fast-water rheophiles demand.
No specific husbandry guidance beyond these general inferences from ecology and water chemistry data can be offered.
Conservation
The IUCN Red List assessed Dolichancistrus carnegiei as Least Concern (LC) on 9 October 2014, with no major threats identified at the time of assessment. The Magdalena River basin, however, is one of the most modified freshwater systems in South America — subject to agricultural runoff, deforestation, sedimentation, urban growth, and hydroelectric development that alter river hydrology and substrate character.
The 2014 assessment predates more recent documentation of ongoing habitat degradation in the upper and middle Magdalena. As a species likely dependent on clear, fast-flowing, rocky-bottomed Andean tributaries, D. carnegiei may be more sensitive to water quality decline and altered hydrology than a Least Concern listing implies; a reassessment with updated field data would be informative. The species is endemic to Colombia and is not known from any protected area or in captive populations.