Agulhas redfin's ancient journey

The fish has been formally named, underscoring the urgent need for the conservation of freshwater systems and the species that call them home

- Sheree Bega

Net value: Environmental worker Breyton Murtz does research in the Nuwejaars River in the Western Cape. Photo: Supplied

(Supplied)

A small freshwater fish species has been slowly evolving — nameless and unknown — in the rivers at Africa’s southernmost tip. Now, at last, the only redfin living in this region not only has a name but has been formally described.

The redfins found in the Heuningnes River system, including the Nuwejaars River and its tributaries around the towns of Bredasdorp, Elim and Agulhas, have now been officially named Pseudobarbus agulhas — the Agulhas redfin.

Scientists had already discovered that these fish formed their own distinct lineage but, until recently, they were only referred to informally as the Heuningnes redfin (Pseudobarbus sp. 'Heuningnes').

The species’ official recognition was confirmed in a newly published scientific paper, authored by Fatah Zarei, Melissa Martin, Paul Skelton and Albert Chakona, from the NRF-South African Institute for Aquatic Biodiversity (Saiab).

“We confirmed that the Agulhas redfin (Pseudobarbus agulhas) is a distinct species based on three independent lines of evidence: genetics, morphology and distribution,” Zarei said.

Genetically, all individuals and populations of this species form a single, well-supported lineage that is clearly distinct from all other redfins: “Morphologically, it can be distinguished from the other 14 known redfin species by a unique combination of traits,” he said.

“These include two pairs of slender barbels near the mouth, absence of linear body speckles, a relatively narrow head, specific scale counts, a characteristic pattern of small tubercles on the heads of breeding males and usually a single tooth in the outer row of the throat teeth.”