)
)
)
At Africa’s southernmost tip, rivers stained dark by peat may look unassuming. But they shelter some of the most range-restricted freshwater fish on Earth – species found nowhere else, and now among the most threatened globally.
Only in recent decades have scientists and researchers started to understand just how vulnerable these fish are. What they’ve discovered is concerning: without urgent conservation intervention, several of these species are likely to disappear, possibly even within our lifetimes.
A hotspot hidden in plain sight
The Nuwejaars River system, along with its tributaries and surrounding wetlands in South Africa’s Western Cape, supports three endemic species. They form part of a collective known as “fynbos fish” because they occur within the Fynbos Biome, a globally recognised biodiversity hotspot:
- Agulhas Redfin (Pseudobarbus agulhas) – Endangered
- Heuningnes Galaxias (Galaxias sp. nov. ‘heuningnes’) – Endangered and listed on SHOAL’s 1000 Fishes initiative
- Agulhas Kurper (Sandelia sp. nov. ‘agulhas’) – yet to be formally described and currently classified as Data Deficient
The redfin and galaxias occupy an extremely small geographic range – in some cases limited to a handful of sites – making them especially vulnerable to environmental disturbance.
What our monitoring found
Historically, knowledge of these fish came from sporadic academic surveys. That changed in 2024, when the Nuwejaars River Nature Reserve (NRNR) began systematic monitoring across the Nuwejaars Wetlands Special Management Area – a 47 000-hectare conservation landscape of privately owned land that contains one of South Africa’s largest remaining wetland systems.
With funding support from Fondation Segré through the International Union for the Conservation of Nature (IUCN), trained environmental monitors were deployed by the NRNR, the non-profit company that manages the entire Nuwejaars Wetlands Special Management Area. They started to track fish abundance, distribution and habitat condition. In 2025, this work expanded through further support from the Mohamed bin Zayed Species Conservation Fund.
By early 2026, results revealed just how precarious the situation is. The entire catchment area of 72,500 hectares was assessed, which includes 15 rivers in total, or around 670kms of river. Of this, Agulhas Redfins were found in very small numbers in three river stretches in the Nuwejaars Wetlands SMA in an area totalling just 11kms. What’s more, fewer than 250 individuals were found. Heuningnes Galaxias were a little more widespread, occurring in nine rivers. However, fewer than 1,000 individuals were recorded. For species with such narrow ranges, these numbers signal real extinction risk.
Invasive species: the dominant threat
The most immediate pressure comes from invasive alien fish introduced over the past century. These include:
- Spotted Bass (Micropterus punctulatus)
- Mirror Carp (Cyprinus carpio)
- Bluegill Sunfish (Lepomis macrochirus)
- Mozambique Tilapia (Oreochromis mossambicus)
These species prey directly on indigenous fish, compete for food and alter aquatic habitats. In river systems as small and specialised as these, even limited invasions can be catastrophic.
Climate extremes compound the crisis
Climate change is intensifying pressures. In September 2023 and June 2024, the region experienced two major flood events, affecting river channels and eroding banks. The damage was worsened by invasive alien plants along river banks, which uproot easily during floods and destabilise soils.
Now, in 2026, the system is experiencing extremely dry conditions. Historically, deep pools would have provided dry-season refuge for fynbos fish. But erosion has reduced pool depth and persistence, leaving fish increasingly exposed.
In combination, invasive species and climate volatility are eroding the last refuges these fish depend on.
A recovery action plan
Beyond documenting the species populations, the NRNR team and partners are actively implementing recovery interventions. This work is carried out alongside the NRF-South African Institute for Aquatic Biodiversity, Fynbos Fish Trust, CapeNature (the provincial conservation authority) and the Freshwater Research Centre.
As an emergency measure, Agulhas Redfin individuals have already been relocated across the Nuwejaars Wetlands system into two off-stream dams. These dams are free from invasive fish and deep enough to remain viable refuges through dry summers.
In parallel, planning is underway to establish a permanent river sanctuary within the species’ historical range. This requires:
- Environmental impact assessments
- Construction of a fish barrier
- Removal of invasive species
- Reintroduction of indigenous fish
It is technically complex and costly but represents the most viable long-term solution. The NRNR is therefore working to secure the funding needed to make this conservation effort possible – no small task in a country where freshwater biodiversity has historically been underfunded, despite South Africa having one of the highest rates of freshwater fish endemism in the world. The Mohamed bin Zayed Species Conservation Fund has once again stepped in, providing a vital launchpad for further fundraising efforts.
Expanding beyond our footprint
In 2026, NRNR’s focus also extends beyond the Nuwejaars Wetlands Special Management Area itself. Monitoring is being expanded into the Kars and Hansies Rivers, both connected to the system via the Heuningnes River. These tributaries may hold undiscovered refuge populations, reveal species strongholds or show further declines.
This landscape-scale approach is critical in South Africa, where most freshwater systems flow through privately owned land, making conservation success dependent on collaboration – not only with landowners, but also with peer conservation organisations.
It starts with community
Long-term success will not be achieved through ecological interventions alone. The NRNR’s work includes environmental education programmes for children from rural communities in the area, alongside engagement with landowners and farmers whose stewardship directly influences river health.
In a country where biodiversity conservation and social equity are intertwined, this collaborative model is essential. Protecting these fish also means protecting water quality, wetlands and ecosystem services that support agriculture and rural livelihoods.
Our global role in this small corner
These fish may inhabit a remote corner of southern Africa, but they are globally important. Their extinction would mean the disappearance of entire evolutionary lineages found nowhere else on Earth. And while the rivers in the Nuwejaars have supported these species over millennia, even as the environment has changed, their survival now depends on the speed and scale of our conservation action.
)
