Taxonomy & naming
Otothyropsis biamnicus was described by Calegari, Lehmann A. and Reis in 2013 in Zootaxa (volume 3619, number 2, pages 130–144), in a paper presenting two new cascudinhos of the genus Otothyropsis from the rio Paraná basin. The Catalog of Fishes (Eschmeyer, CAS) recognises the species as valid.
The genus Otothyropsis belongs to the subfamily Hypoptopomatinae, the small armoured catfishes known in Brazil as cascudinhos. Otothyropsis biamnicus is diagnosed by a short pectoral-fin spine (18.6–21.3% of standard length), a triangular dorsal-fin spinelet, and an elongated body.
Morphology
Otothyropsis biamnicus reaches about 1.5 in standard length. It has the elongate, plate-armoured body and ventral suckermouth typical of Hypoptopomatinae. Fin counts are dorsal ii,6–7 and anal i,5, with 28 vertebrae. It is distinguished from congeners by its short pectoral-fin spine, triangular dorsal-fin spinelet and elongated body form. No information on sexual dimorphism has been published for this species.
Habitat
Otothyropsis biamnicus occurs in tributaries of the rio Iguaçu (in Santa Catarina and Paraná states) and of the rio Tibagi (in Paraná state), within the upper rio Paraná basin, southern Brazil. The environment is freshwater, demersal and tropical.
A distinctive ecological note: the species has been recorded as commensal with chironomid (midge) larvae, which attach to its gill opening or, more rarely, to the posterior process of the cleithrum. No published water-chemistry measurements (temperature, pH, hardness) are available for the localities.
Feeding
No direct diet study has been published for Otothyropsis biamnicus. As with the rest of the genus, it is presumed to be a herbivore/detritivore that grazes biofilm, algae and fine detritus from submerged surfaces, but dietary data are sparse.
Mating
No data on courtship or mating behaviour have been published for this species.
Breeding
No breeding data have been published for Otothyropsis biamnicus. The species is not known to have been bred in aquaria.
In the aquarium
Husbandry data for Otothyropsis biamnicus are sparse; the species is not established in the ornamental trade and no documented aquarium experience exists. As a small grazing cascudinho from tropical stream systems, it would in principle require clean, oxygenated water and grazing surfaces, but specific care recommendations would be speculative.
Conservation
The IUCN Red List assessed Otothyropsis biamnicus as Least Concern in 2018. Its distribution across two separate drainages — the Iguaçu and the Tibagi — gives it a broader range than some congeners, and it is not currently considered threatened, though it remains dependent on the integrity of its upper Paraná tributary habitats.