P.sper has a single pair of barbels and compared to its sister species the intestine is considerably longer and involuted. The males are easily recognizable during the breeding season with a dark red fins and breeding tubercles on the head. It occurs in turbid, eutrophic waters with silt to boulder substratums in the Karoo. It is a minnow and small size is known to be an adaptation to a highly variable environment as it makes new food sources available by allowing ready access to spatially restricted habitats. It also has a long gut relative to its sister species which feeds mainly on invertebrates.
Juveniles inhabit sheltered areas such as erosion gullies and vegetated areas in streams.
In the Karoo sections of both the Gamtoos and Gourits Rivers this minnow has to be adapted to a riverine system with very erratic flows, prolonged droughts, devastating floods and high silt loads. Can have a life span of up to 3 years compared to its sister species, P. afer with up to 6 years. The combination of life-history attributes, gonadosomatic index, fecundity, egg size, investment per clutch, number of clutches per season and reproductive lifespan was found to be different for the Pseudobarbus species which lives in the arid interior, P. asper , than for the species, P. afer, which inhabits the more perennial rivers of the Gamtoos River system. P. asper has both an early maturity and a high reproductive rate which enables it to quickly recolonize areas. Peak spawning usually occurs after periods of steady rainfall.