SANBI

habitat_narrative

Freshwater (=Inland waters)

The Smallscale Redfin prefers mainstream areas that drain mostly over Bokkeveld marine sediments, yielding water with high mineral content and is often turbid (Skelton 2001). Cambray (1994) studied the reproduction biology of the Smallscale Redfin and its sister species, the Eastern Cape Redfin (Pseudobarbus afer) in the greater Gamtoos River System. Pseudobarbus asper is restricted to turbid, alkaline Karoo-type rivers within the system. The species exhibited a protracted spawning season, ranging from October to April (Cambray 1994). Spawning is induced by increased river flow either from rainfall or flow releases from large dams. The Smallscale Redfin spawns non-adhesive eggs on coarse substrate. Once the eggs are spawned and fertilised, parental care is absent. Eggs are generally deposited under boulders in mid channels. Breeding was observed upstream of pools in rivers, with free embryos and larvae drifting into pools and feeding in the pelagic zone. Free embryos exhibited negative phototaxis, changing to positive phototaxis during swim-up period (approximately 4.2 days). Shorter times to first feeding in Smallscale Redfin was observed compared to Eastern Cape Redfin.
Cambray (1994) further reported that the Smallscale Redfin compared to the Eastern Cape Redfin and a highly significant relationship between body mass and fecundity. Males of the Smallscale Redfin mature at 41-42 mm SL and females mature at 43 mm. Sexual maturity in the Smallscale Redfin was generally reached in their second year of life, compared to Eastern Cape Redfin, which only matured in their third year. A higher gonadosomatic index (GSI) was generally observed in the Smallscale Redfin along with the production of more, smaller eggs for a longer reproductive season. The life history strategy of the Smallscale Redfin represents the species’ adaptation to a less stable environment.

Red List of South African Species

Notes

habitat_narrative

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