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Abstract
Only one large yellowfish species occurs in the Hardap Dam, apparently closely related to Barbus kimberleyensis. Though smaller than this species in the Vaal River, it is nevertheless a valuable and abundant angling fish. After maturity, reached in females at 26 cm and in males at 18 cm fork length, females outnumber males by 9 :1 beyond 30 cm. Main spawnings occur between February and April, some four months later than in the Vaal River, being correlated with peak seasonal rains in both cases. A minor spawning later in the year is usual, with improved fry survival due to warmer weather conditions reducing the winter mortality of the earlier spawned young. Breeding sites are probably in lentic gravelly-bottomed areas within the dam. Egg production increases from 5-6 000 in 30 cm fish to ca 47 000 in 60 cm females, with strong relationship between cube of fish length and fecundity.
