Taxonomy & naming
Chaetostoma jegui was described by Lucia Rapp Py-Daniel in 1991 in Ichthyological Exploration of Freshwaters (volume 2, number 3, page 240, figure 2). The type locality is the Rio Uraricoera at Maracá Island (3°21'N, 61°26'W), Federal Territory of Roraima, Brazil — now Roraima State. The species is accepted under this combination by the Catalog of Fishes (Eschmeyer, CAS). No L or LDA number has been assigned.
The genus Chaetostoma belongs to the tribe Chaetostomini within subfamily Hypostominae. Chaetostoma is a South American genus of primarily rheophilic, algae-scraping loricariids distributed from Andean foothills and adjacent shield drainages across northern South America — sometimes called 'rubbernose plecos' or 'bulldog plecos' in the trade, for the broad, flattened snout characteristic of the group.
The epithet jegui honours Dr Michel Jégu, an ichthyologist who worked at ORSTOM (the French Office de la Recherche Scientifique et Technique Outre-Mer, now IRD), the French overseas scientific research organisation. Jégu made significant contributions to the ichthyology of Amazonian and Guiana Shield rivers, and his work on Roraima's fish fauna provided a foundation for the type series collection.
Morphology
Chaetostoma jegui reaches a maximum recorded size of 6.5 in standard length (SL). The body form is typical of the genus: dorsoventrally flattened with a broad, rounded snout — the 'rubber nose' profile — and a wide, powerful suckermouth equipped with numerous fine, elongate, spatulate teeth adapted for scraping algae from hard surfaces in fast current. As in all loricariids, the body is encased in bony dermal scutes.
The species is distinguished from all other members of Chaetostoma by three diagnostic characters recorded by Rapp Py-Daniel (1991): a dermal keel on the posterior tip of the supraoccipital bone (unique in the genus); a reduced number of interopercular odontodes (only 2–5, compared with more in congeners); and the presence of three smooth, large, digitiform papillate projections in the buccal cavity.
Sexual dimorphism is documented. Males have a larger and proportionally broader head, slimmer ventral body profile, and disproportionately large pelvic fins compared with females. This head-broadening in males is consistent with the pattern seen in many Chaetostoma, where the broad head houses larger buccal musculature used in nest-fanning behaviour during breeding.
Habitat
Chaetostoma jegui is known from the Rio Branco drainage of Roraima, Brazil, specifically the Uraricoera and Tacutu rivers — two major right-bank tributaries of the Rio Branco that drain the Guiana Shield south of the Venezuelan border. The type locality, Maracá Island on the Rio Uraricoera, lies within the Maracá Ecological Station, a federal protected area of considerable ecological significance.
The Uraricoera is a typical Guiana Shield river: clear to slightly tannin-stained, with a rocky or sandy substrate, seasonally variable discharge, and stretches of fast current over exposed bedrock and boulders. Chaetostoma species are nearly always associated with such rheophilic conditions — fast, well-oxygenated, clear water running over hard substrate. Algal growth on current-exposed rocks is the primary food resource. No specific field measurements of temperature or pH are available for the collection sites, but Roraima's rivers in this region are typically soft, slightly acidic to near-neutral, and relatively cool in the dry season due to highland influence.
The presence of the type locality within a protected ecological station provides habitat security for at least part of the species' range.
Feeding
Chaetostoma jegui is a dedicated algae scraper. Like other rubbernose plecos, it uses its broad suckermouth and numerous fine teeth to graze periphyton — the community of algae, diatoms, cyanobacteria, and associated organic films — from the surfaces of current-swept rocks. The powerful suction of the mouth allows it to maintain contact with substrate even in fast current while feeding. Organic detritus and fine plant material are also ingested incidentally.
In the aquarium, the diet should be strongly plant-based. High-quality sinking algae wafers and spirulina-based pellets are the foundation; blanched courgette (zucchini), cucumber, and spinach are readily accepted. The fish benefits from the presence of flat smooth stones or slate surfaces that develop natural algae growth under moderate to strong lighting. Protein-heavy foods should be offered sparingly; excessive animal protein is not appropriate for this primarily herbivorous catfish.
Mating
Males of C. jegui are recognisable by their proportionally larger, broader head, slimmer ventral body, and enlarged pelvic fins — secondary sexual characters that become more pronounced in mature, well-conditioned individuals. Females are broader-bodied ventrally when gravid.
Mating behaviour has not been described in detail for this species in published sources, but Chaetostoma typically display the rheophilic cave-spawning pattern common to Loricariidae: males establish and defend spawning territories in shallow, fast-flowing areas with flat overhanging surfaces or rocky crevices. Courting involves the male positioning himself beneath a suitable flat object and encouraging the female to enter.
Breeding
PlanetCatfish records document that C. jegui spawns in shallow, fast-flowing water under flat objects. The adhesive egg clutch is deposited on the underside of the flat surface, and the male guards the clutch upside-down, covering the eggs with his body and fanning them to maintain oxygen supply. This inverted posture — the male pressed against the eggs from below while suspended in fast current — is characteristic of rheophilic loricariids that breed in exposed, current-swept microhabitats.
No clutch size data are recorded for this species. Fry can be presumed to require well-oxygenated, fast-flowing water and to begin feeding on algal surfaces immediately after becoming free-swimming, consistent with the biology of the group. Successful captive breeding would require replicating fast-current conditions with appropriate flat spawning surfaces.
In the aquarium
Chaetostoma jegui is a rheophile that demands clean, fast-moving, well-oxygenated water — this is not negotiable. Poor water movement or elevated nitrate will stress the fish and compromise immune function. Efficient filtration rated well above the tank volume, and ideally a powerhead or additional circulation pump creating a directed current, are essential.
At up to approximately 6.5 in SL, a single adult can be accommodated in a tank of around 30–40 US gal, provided the filtration and current requirements are met. The tank should be furnished with smooth, flat stones (slate works well), a sandy or fine gravel substrate, and minimal decoration that would impede current flow. Driftwood can be included but is not essential.
Water parameters should reflect the Guiana Shield origin: temperature approximately 72–79 °F, pH 6.0–7.5, soft to moderately soft water, and high dissolved oxygen. Regular partial water changes — at least 30–40% weekly — are important for maintaining the water quality this species requires.
Chaetostoma jegui is generally peaceful toward other species and can be kept in community tanks with small to medium-sized fish that tolerate similar fast-water conditions. Multiple individuals can be kept together if sufficient space and algae-covered rock surfaces are available; males may show some territorial behaviour around preferred grazing sites but serious aggression is uncommon in a well-furnished tank. The species is not recommended for standard community aquariums with still-water-adapted fish.
Conservation
The IUCN Red List assessed Chaetostoma jegui as Least Concern (LC) on 7 November 2018. The species occurs in the Rio Branco drainage (Uraricoera and Tacutu rivers) of Roraima, Brazil, and no major threats have been identified. The IUCN assessment notes that the Maracá Island type locality is protected within the Maracá Ecological Station, providing meaningful habitat security for at least part of the range.
Roraima's rivers remain among the least disturbed in Brazil's Amazon system, benefiting from relatively low population density and limited agricultural development compared with southern Amazonian states. Nonetheless, illegal gold mining (garimpo) in Roraima's river systems — including the Uraricoera — poses a recognised threat to aquatic communities through siltation and mercury contamination. The impact on C. jegui specifically has not been quantified, but rheophilic algae grazers dependent on clean, clear water are among the most sensitive groups to sedimentation.