Taxonomy & naming
Parotocinclus bahiensis was described by Miranda Ribeiro in 1918, placed in the family Loricariidae and subfamily Hypoptopomatinae. The original type specimens are reported as lost (Britski, 1969), which complicates later taxonomic comparison.
The genus name Parotocinclus combines Greek para (beside), ous/otis (ear), and kygklos (a small fish), while the epithet bahiensis refers to the Brazilian state of Bahia. Beyond the original description and the note on the lost types, no further taxonomic revision is covered in the sources consulted here.
Morphology
Parotocinclus bahiensis is very small, reaching about 1 in in standard length — among the most diminutive of the eastern Brazilian loricariids. It carries the typical loricariid armour of bony scutes and the ventral sucker-mouth of an algae-grazing catfish.
Detailed morphometrics, fin-ray counts, and coloration are not available in the sources consulted here, in part because the original type material is lost. Sexual dimorphism has not been described for the species in these sources.
Habitat
The species occurs in the coastal drainages of Bahia, in eastern Brazil. It is a freshwater, demersal (bottom-associated) fish of tropical waters. As with other Parotocinclus, facultative air-breathing has been reported in the genus, allowing supplementary uptake of atmospheric oxygen. Specific data on water chemistry, depth, and current at its localities are not published in the sources consulted here.
Feeding
Parotocinclus bahiensis has a trophic level of about 2.4, consistent with a grazer or algivore. Like other dwarf loricariids, it rasps algae and biofilm — together with associated micro-organisms and detritus — from submerged surfaces. A dedicated diet study for the species is not available in the sources consulted here.
Mating
No courtship or mating behaviour has been documented for Parotocinclus bahiensis in the sources consulted here.
Breeding
No reproductive data — spawning mode, clutch size, or parental care — has been published for Parotocinclus bahiensis in the sources consulted here.
In the aquarium
Parotocinclus bahiensis is not an established aquarium species, and no husbandry account is available in the sources consulted here. Small Parotocinclus in general are peaceful, biofilm-grazing fish suited to mature, well-oxygenated planted tanks, but specific care parameters for this species cannot be given without data.
Conservation
The IUCN Red List assessed Parotocinclus bahiensis as Least Concern, with the assessment dated 7 November 2018. No specific threats or population trends for the species are detailed in the sources consulted here. As a Bahian coastal-drainage fish, it shares the general pressures on eastern Brazilian Atlantic-slope streams, but no species-level concern is recorded.