Taxonomy & naming
Panaqolus claustellifer was formally described by Milton Tan, Leandro S. de Souza, and Jonathan W. Armbruster in 2016 in Neotropical Ichthyology, volume 14, number 2 (article e150033, pp. 1–8). The holotype (CSBD F1702 / AUM 44721, adult male, 2.5 in SL) and two paratypes (AUM 47717, AUM 65708) were collected from the Takutu River near Lethem, Guyana (3.47043°N, 59.80993°W); an additional paratype (MZUSP 33704) was taken from the mainstem rio Branco, Roraima, Brazil. The Catalog of Fishes (Eschmeyer, CAS) records the combination Panaqolus claustellifer Tan, de Souza & Armbruster, 2016 as valid with no synonyms.
The species was known to the hobby as L306 and LDA064 long before formal description — photographs of the fish circulated as an undescribed Panaqolus sp. from the rio Branco drainage for many years before the Tan et al. (2016) paper resolved its identity. Within Panaqolus, P. claustellifer belongs to the barred species group and can be distinguished from other barred congeners by its consistently 5 trunk bars that do not increase with size, its characteristic anteroventral-to-posterodorsal bar orientation, and by the keyhole-shaped pattern of lines on the snout — the feature that inspired the species name. Phylogenetically, Tan et al. (2016) inferred that the species originated in the Amazon and dispersed into the Takutu River after an Amazon capture of part of the Proto-Berbice drainage rerouted the upper Takutu headwaters.
Morphology
Panaqolus claustellifer is a compact loricariid reaching approximately 2.5 in standard length in the type series per FishBase; PlanetCatfish lists the maximum at 3.5 in SL (3.5 in), consistent with most hobbyist records. Total length is typically 4–4.5 in. The body is fully plated in bony loricariid scutes, fusiform and moderately depressed. The pattern is its most striking feature: the ground colour is a warm reddish-brown to dark brown overlaid with 5 pale cream to tan vertical bars on the trunk, with the bars oriented in an anteroventral-to-posterodorsal direction. The fins are banded with dark and pale alternating elements that continue the body's barred theme. The head bears lines of brown on a lighter background radiating from behind the eye toward the snout margin, which in larger specimens bifurcate mid-line to create a keyhole-shaped pale area — the feature that Tan et al. named the species after (Latin: claustellum = keyhole, fero = to bear).
Dorsal-fin formula: 2 spines plus 7 soft rays; anal-fin: 5 soft rays. The dentition is spoon-shaped with small lateral cusps — characteristic of Panaqolus and appropriate for rasping wood and biofilm surfaces — and the dentaries form an acute angle of approximately 70°, one of the characters distinguishing P. claustellifer from species with nearly parallel dentaries. Sexual dimorphism follows the genus pattern: breeding males develop elongated interopercular odontodes and noticeable dorsal odontodes; the male's genital papilla is small and pointed while the female's is large, rounded, and swollen when mature. Gravid females are notably wider between the pectoral and pelvic fin bases when viewed from above.
Habitat
Panaqolus claustellifer is known from the Takutu River near Lethem, Guyana, and the mainstem rio Branco in Roraima, Brazil — the only Panaqolus recorded from the Branco drainage (which feeds the Rio Negro). The Takutu is a clearwater river draining the Rupununi savanna of southern Guyana; it crosses the Brazil–Guyana border near Bonfim/Lethem and joins the Surumu to form the upper Branco. Field imagery associated with the original description (Catfish Study Group Journal, 2016) shows a diverse habitat on the rio Takutu: rocky and sandy substrate sections with submerged wood accumulations, moderate current, and clear water over a pale sandy-brown bed.
Water parameters in the Takutu–Branco system are typical of clearwater Amazonian tributaries: moderately warm (approximately 79–86 °F), slightly acidic to near-neutral (pH 6.0–7.2), with low to moderate hardness. The species' distribution across the rio Branco–rio Negro divide places it in a biogeographically interesting zone where the black- and clearwater faunas meet. Microhabitat is associated with submerged wood accumulations and rocky interstitials — appropriate for a xylophage that depends on driftwood as both food and shelter.
Feeding
Panaqolus claustellifer is a true xylophage. Like P. maccus and other members of the genus, it feeds on submerged wood by rasping the surface with its spoon-shaped teeth, ingesting wood fibres along with the biofilm of bacteria, fungi, and detritus colonising the wood. The nutritional contribution of the cellulose itself is relatively modest; gut bacteria capable of fermenting hemicellulose fractions are understood to be important to digestion in wood-eating Panaqolus and Panaque. Multiple sources confirm that this species requires wood to rasp — it is a dietary requirement, not optional enrichment.
PlanetCatfish recommends a primarily vegetarian supplementary diet: algae wafers, spirulina discs, courgette (zucchini), and root vegetables such as sweet potato and potato are accepted and appropriate. The genus generally should not be fed heavily on protein-rich animal foods; a predominantly vegetarian supplementary ration alongside ad libitum access to driftwood reflects the natural dietary balance. Several pieces of wood of different species (e.g., a mix of catappa/Indian almond wood, mopani, Malaysian driftwood) are preferable to a single piece, both for palatability variation and to ensure continuous rasping opportunity.
Mating
Mating in Panaqolus claustellifer follows the well-documented pattern for the genus. Males become territorial around preferred cave or crevice sites within the wood and rockwork, patrolling and displaying elongated interopercular odontodes to rival males. Territorial skirmishes between males typically resolve through display and minor odontode contact rather than prolonged fighting, provided sufficient hiding space and visual barriers are available. Males may be kept with multiple females in suitably large tanks; two males in a small tank risk chronic conflict.
Female readiness is signalled by a swollen, rounded papilla and noticeably broadened mid-body profile. Hobbyist breeding accounts on PlanetCatfish (7 registered breeding reports) describe conditioning adults with a varied diet, performing regular large water changes, and occasionally slightly lowering temperature to simulate the seasonal wet-season pulse — all measures that mimic natural inundation cycles in the Branco–Takutu drainage. Increasing current at the time of conditioning is also noted as useful by hobbyists familiar with the closely related P. maccus and P. changae.
Breeding
Panaqolus claustellifer is a cave spawner with paternal brood care — the standard Panaqolus breeding mode. PlanetCatfish records 7 breeding reports for this species as of 2026, reflecting its relative accessibility in the hobby. The male selects and defends a narrow cave or hollow — a tight section of driftwood, a ceramic breeding tube, or a PVC pipe — and after spawning he remains to fan the eggs with his fins and guard the clutch against disturbance. Females do not participate in post-spawning care.
The clutch is deposited as adhesive eggs on the interior surfaces of the cave. Egg colour and exact clutch size figures are not well-documented for P. claustellifer specifically, but by analogy with P. maccus (a close relative for which data exist) clutch sizes of 20–50 eggs at typical tank temperatures are plausible. Incubation likely takes 5–7 days at 79–82 °F. Fry emerge looking like miniature adults with the tiger-stripe pattern visible from the outset; they begin rasping wood and fine prepared foods almost immediately. The male continues to guard the fry for some days after emergence. Rearing fry on algae wafers, soft vegetable matter, and very fine driftwood shavings is straightforward; separate growout containers help ensure survival if tankmates are present.
In the aquarium
At a maximum of about 3.5–4 in SL (4.5 in TL), Panaqolus claustellifer is a genuinely small pleco well within the reach of moderately sized aquaria. A single adult is manageable in 15–20 US gal, while a small group of three to six individuals can be housed comfortably in 30–40 US gal provided multiple cave structures and wood tangles are distributed to minimise intraspecific tension. Per PlanetCatfish guidance, approximately a 30 × 12 in territory per individual is a reasonable spacing allowance for group keeping.
Water parameters should reflect the clearwater Takutu–Branco origin: temperature 77–84 °F, pH 6.0–7.5, low to moderate hardness (GH up to about 15°dH is tolerated, though softer water is preferred). The species is not as extreme in its blackwater chemistry demands as some Rio Negro endemics, making it somewhat more flexible than P. maccus in a community context — but soft, clean water with good flow and high oxygen remains the ideal.
Driftwood is mandatory — without it the fish will be chronically stressed and nutritionally compromised. Multiple wood types are preferable. Plants are largely safe (this fish is not destructive to vegetation in the manner of Pterygoplichthys), and robust attached plants like Anubias on wood complement both the aesthetic and the territorial complexity of the setup. Tankmates should be peaceful mid-water or open-water species that will not compete aggressively for the bottom: small tetras, rasboras, dwarf cichlids, and Corydoras are all appropriate. The species is not suitable for a meticulously planted aquascape where bare substrate or delicate carpet plants are priorities, since wood debris and rasping activity create some disturbance near feeding sites.
Conservation
Panaqolus claustellifer was assessed as Least Concern (LC) by the IUCN Red List in November 2023, reflecting a stable known distribution across the Takutu River and rio Branco system in Brazil and Guyana and no identified major threats to the population. The species was only formally described in 2016, and the conservation assessment is still relatively recent; population size estimates have not been published.
The rio Branco and Takutu drainage systems face lower industrial pressure than the Xingu or Madeira, but are not without risk: the Roraima state of Brazil has experienced agricultural expansion and sporadic gold-mining activity that contributes sediment and mercury loading to rivers in the region. The Takutu–Ireng river border zone has been a site of some environmental tension around land use and indigenous territorial rights (Macuxi territory), and any large-scale land-clearing in the Rupununi savanna headwaters could affect the clearwater character of the Takutu. However, at present there is no documented evidence of population decline, and the species appears naturally local in distribution but not critically rare. In the aquarium hobby, tank-bred specimens are increasingly available given the seven or more documented breeding events; sourcing captive-bred fish is advisable where possible.