Taxonomy & naming
Parotocinclus halbothi was described by Lehmann A., Lazzarotto and Reis in 2014, in Neotropical Ichthyology (volume 12, number 1, pages 27–33). The Catalog of Fishes (Eschmeyer, CAS) recognises the name as valid (species id 73245).
The species belongs to the subfamily Hypoptopomatinae, the group of small armoured suckermouth catfishes within Loricariidae. Parotocinclus is a speciose genus of dwarf loricariids distributed widely across eastern and northern South America.
The species is distinguished by a suite of characters noted in the original description: a cheek canal plate elongated posteriorly along the ventral surface of the head so that it contacts the cleithrum; the absence of a triangular dark patch on the anterior dorsal-fin membrane; unicuspid accessory teeth on both the premaxilla and dentary; the absence of a Y-shaped light mark on the snout; small circular median abdominal plates arranged in four to seven irregular longitudinal series; and a rudimentary adipose fin lacking a membrane.
Morphology
Parotocinclus halbothi is a very small loricariid, reaching about 1 in standard length — one of the smallest species in the genus. The body bears the overlapping bony plates (scutes) typical of the family.
Fin counts recorded in the description are a single dorsal spine with seven branched dorsal rays and six branched anal rays. The abdomen carries small circular median plates in four to seven irregular longitudinal series. The adipose fin is rudimentary and lacks a membrane.
Diagnostic external features include the posteriorly elongated cheek canal plate contacting the cleithrum, unicuspid accessory teeth on the premaxilla and dentary, the absence of a triangular dark patch on the anterior dorsal-fin membrane, and the absence of a Y-shaped pale snout mark. No data on sexual dimorphism has been published for this species.
Habitat
The species is known from the Trombetas River basin in Brazil and the Marowijne (Marowijne/Maroni) River basin in Suriname, on opposite flanks of the Guiana Shield. It lives in clear-water streams without aquatic vegetation.
The type-locality stream had an average width of about 10 ft, with channel depth reaching 22 in in the rainy season and 16 in in the dry season. Water velocity ranged from roughly 1–2 ft/s, conductivity was very low (10–11 µS/cm), and dissolved oxygen was high (6.16–7.6 mg/L). Recorded pH was acidic, around 4.9–5.0, at a tropical temperature near 79 °F. The substrate consisted of fine white gravel, coarse sand and leaf litter; the fish were found in the deeper parts of the main channel over gravel.
Like other members of the genus, P. halbothi is a facultative air-breather, able to supplement gill respiration with atmospheric air.
Feeding
No diet study has been published for Parotocinclus halbothi. Members of the genus Parotocinclus are typically grazers of aufwuchs — the film of algae, diatoms, biofilm and associated micro-organisms that coats submerged surfaces — rasped from rocks, gravel and leaf litter using the suckermouth. Given the gravel-and-leaf-litter substrate of its clearwater habitat, a comparable grazing habit is plausible, but specific dietary data for this species is not available.
Mating
No data on courtship or mating behaviour has been published for Parotocinclus halbothi.
Breeding
No reproductive or breeding data has been published for Parotocinclus halbothi. The species is not known to have been bred in aquaria.
In the aquarium
Parotocinclus halbothi is not established in the aquarium hobby, and no husbandry information has been published for it. Any keeping notes would be inferred from its natural habitat rather than from documented practice: a very small fish from cool, soft, highly acidic (pH about 4.9–5.0), oxygen-rich, low-conductivity clearwater streams with moderate flow over fine gravel, sand and leaf litter. Reproducing those parameters — soft acidic water, strong oxygenation and gentle current — would be the starting point for any attempt, but the species should be regarded as undocumented in captivity.
Conservation
Parotocinclus halbothi has not been evaluated by the IUCN Red List (status Not Evaluated, per FishBase, version 2025-2). No formal assessment of its population or threats exists. Its known range spans clearwater streams in the Trombetas basin (Brazil) and Marowijne basin (Suriname); as with many small, narrowly documented Guiana Shield fishes, the chief general concerns for such habitats are deforestation, mining-related sedimentation and changes to stream hydrology, though none has been specifically assessed for this species.