Taxonomy & naming
Parotocinclus robustus was described by Lehmann A. and Reis in 2012, in Zootaxa (number 3390, pages 56–64). The Catalog of Fishes (Eschmeyer, CAS) recognises the name as valid (species id 72348).
The species belongs to the subfamily Hypoptopomatinae, the dwarf armoured suckermouth catfishes within Loricariidae, and to the large genus Parotocinclus.
Its most distinctive feature is an abdomen completely devoid of dermal plates between the pectoral girdle and the anus — a condition shared within the genus only with P. prata. Additional diagnostic characters include a ventral head surface behind the lower lip that is smooth and without rugosities in adults, postrostral plate 4 contacting infraorbitals 3 and 4, and the development of many dark brown dots on the dorsal and lateral surfaces of the head and trunk in large specimens.
Morphology
Parotocinclus robustus reaches about 1.5 in standard length. The body carries the family's overlapping bony plates, but — as the diagnosis emphasises — the abdomen is entirely free of dermal plates between the pectoral girdle and the anus.
Fin counts are a single dorsal spine with seven branched dorsal rays and six branched anal rays. In adults the ventral surface of the head behind the lower lip is smooth, without rugosities, and postrostral plate 4 contacts infraorbitals 3 and 4. Large specimens develop numerous dark brown dots on the dorsal and lateral head and trunk. The species epithet alludes to its strong, robust general appearance. No data on sexual dimorphism has been published.
Habitat
Parotocinclus robustus occurs in the upper and middle rio São Francisco basin in Brazil. It lives in small to medium rivers in shallow water about 1–5 ft deep, with slow to medium flow and clear to slightly turbid water.
The bottom is mixed — stones, gravel, sand and sometimes mud — and the fish are found mostly on marginal (bank-edge) vegetation. Like other members of the genus, P. robustus is a facultative air-breather, able to supplement gill respiration with atmospheric air. No specific water-chemistry measurements beyond the tropical, freshwater, demersal classification have been published.
Feeding
No diet study has been published for Parotocinclus robustus. Members of the genus are generally aufwuchs grazers, rasping the algae, diatoms and biofilm coating submerged surfaces with the suckermouth. The species' close association with marginal vegetation suggests it grazes the biofilm and periphyton on plant surfaces, but specific dietary data is not available.
Mating
No data on courtship or mating behaviour has been published for Parotocinclus robustus.
Breeding
No reproductive or breeding data has been published for Parotocinclus robustus. The species is not known to have been bred in aquaria.
In the aquarium
Parotocinclus robustus 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 setting rather than documented practice: a small grazer from shallow (1–5 ft), clear to slightly turbid, slow-to-medium-flow rivers with mixed stone, gravel, sand and mud bottoms, closely associated with marginal vegetation. A planted, gently flowing setup with clean, well-oxygenated water would be a reasonable starting point, but the species should be regarded as undocumented in captivity.
Conservation
Parotocinclus robustus was assessed by the IUCN Red List as Least Concern (assessment dated 7 November 2018, per FishBase, version 2025-2). The species occurs across the upper and middle rio São Francisco basin. While currently classed as Least Concern, the São Francisco system faces pressures from damming, water abstraction and pollution; no threat analysis specific to this species beyond the Red List status is available here.