Oligosarcus perdido Ribeiro, Cavallaro & Froehlich, 2007

Family:  Characidae (Characins; tetras), subfamily: Stethaprioninae
Max. size:  9.78 cm SL (male/unsexed)
Environment:  demersal; freshwater
Distribution:  South America: Rio Perdido in the upper Paraguai basin, Brazil.
Diagnosis:  Dorsal soft rays (total): 11-11; Vertebrae: 39-39. Lateral line with 61-63 scales; scales around caudal peduncle 15-20; and premaxilla without enlarged foramen that accommodates the largest dentary tooth when mouth is closed (Ref. 72405).
Biology:  Found in river where the upper portion is located on a carbonate plateau of about 68 km long. The river in the plateau is dammed by calcareous tufa deposits, forming 1 to 6 m tall sequences of waterfalls. The substrate is composed of many logs, branches and whole trees ling on whitish calcareous clay. Inhabits stretches with sluggish to still waters and appears to occur in low densities. Adults are active from dusk to around 21:00 from near the surface to 2 m deep and always solitary and observed resting after this time along the vertical rocky banks. They remain hidden during the daylight hours. Young fish are observed active during the day, in small groups of 5-6 individuals (Ref. 72405).
IUCN Red List Status: Least Concern (LC); Date assessed: 07 November 2018 Ref. (130435)
Threat to humans:  harmless


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