Freshwater Fish Species: Why Your records Matter
- Jason van den Berg
- Jun 23
- 8 min read
Updated: Jul 4
By Jason van den Berg
When most South Africans think of freshwater fish, exotic species like carp and bass are usually the first that come to mind. But did you know that South Africa is home to more than 200 documented indigenous freshwater fish species?
From the small and often overlooked Straightfin Barb (Enteromius paludinosus) to the well-known Sharptooth Catfish (Clarias gariepinus), our inland waters hold an incredible, and often very underappreciated diversity of native aquatic life.
Unfortunately, many of our indigenous fish species are under growing threat. Habitat loss, pollution, and the spread of invasive alien fish like bass and carp are placing immense pressure on native populations. Even activities such as dam construction, canalization, or poor waste management, can destroy critical habitats and wipe out local populations entirely.
Another major threat is the use of illegal gillnets in our waterways. These nets cause indiscriminate and widespread destruction, harming not just fish populations due to unsustainable harvesting, but also entrapping terrapins, otters, birds, and even crocodiles.
Yet one of the biggest challenges our indigenous species face, is that so few people even know these fish exist, or where they still survive. Their obscurity is part of the problem. Without proper data and public awareness, these species risk slipping away silently. Some perhaps lost before we even understand their role in the ecosystem.
Documenting species is the first step to protecting them. If we don’t know what’s out there or where it still survives, we can’t make informed conservation decisions. Each record helps build a clearer picture of which species are thriving, which are declining, and where urgent action may be needed. Simply put: we can’t protect what we don’t know exists or is still present.
In addition to our projects ranging from snare removal to environmental education, a key focus of Rooikat Conservation is biodiversity monitoring. With the rise of tools like iNaturalist and other user-friendly platforms, it has become easier than ever for the public to contribute to real scientific research. Many anglers, landowners, and others who spend time near rivers and dams encounter species they may not realise are ecologically significant. With just a bit of awareness, a photo, and a shared location, members of the public can provide valuable data, helping scientists and conservationists build a clearer picture of what exists and what needs protecting.
In May this year, we received an interesting report from an angler who caught an African longfin eel (Anguilla mossambica) in Klipvoor Dam in the North West province, complete with a photo and GPS pin. This species hadn’t been noted in the dam for many years, so its presence was a welcome surprise and sparked real excitement among fish enthusiasts. These eels have one of the most fascinating life cycles of any local species, as they live most of their lives in freshwater rivers and dams, but migrate all the way to the Indian Ocean to spawn. The juveniles then return inland, sometimes travelling hundreds of kilometers upstream. Sightings like this not only confirm the continued presence of a rare species, they also highlight the importance of ecological connectivity between our inland waters and the sea.
We're calling on the public to help us fill critical knowledge gaps by reporting all types of aquatic life. From lesser-seen indigenous fish to invasive species like Redclaw Crayfish (Cherax quadricarinatus). Freshwater animals such as crabs, which are important indicators of Cape clawless otters (Aonyx capensis), as well as hippopotamuses (Hippopotamus amphibius), and crocodiles (Crocodylus niloticus) are also of great interest. This information is vital for assessing the health of our freshwater ecosystems and guiding targeted conservation efforts, especially as many species continue to decline.
How You Can Help
Whether you’re an angler, landowner, farmer, avid outdoor enthusiast; anyone who spends time near water, your observations can make a real difference in understanding and protecting our freshwater ecosystems.
Here’s how to contribute:
📸 Take a few clear photos of any interesting or unfamiliar aquatic life you encounter
📍 Pin your location accurately using your phone’s GPS or Google Maps
📲 Upload your sighting to iNaturalist (free on App Store and Google Play)
📤 Or you may send your photo and location directly to us via WhatsApp at 076 982 0471
Examples of valuable reports:
An indigenous Straightfin Barb recorded in a slow-flowing stream near Hammanskraal, with a clear photo and GPS location sent via WhatsApp - “First time seeing this fish.”
A freshwater crab spotted near Rayton, photo and GPS location sent via WhatsApp - “First time seeing a crab here. Is this normal?”
A Largemouth Bass caught in a farm dam near Cullinan, uploaded to iNaturalist — “First time catching this species here after many years of fishing this dam”
An illegal gillnet discovered and removed from the Apies River, with photos and location.
Every record matters. Verified sightings are shared with experts in freshwater ecology and conservation, and contributes to ongoing research. Whether you’re sharing sightings of beautiful native species or alerting us to threats like illegal nets, your contributions are vital to protecting our waterways.
Indigenous Species Spotlight
Celebrating South Africa’s native freshwater life; Unique, ecologically important, and often overlooked.
Straightfin Barb (Enteromius paludinosus)
This hardy, small silvery fish is widely distributed across much of Africa, from Ethiopia and Central Africa to South Africa, including many river systems like the Limpopo and Zambezi. It prefers quiet, well-vegetated freshwater habitats such as lakes, marshes, and slow-flowing streams, feeding on insects, algae, small snails, and detritus. Despite being widespread and common in South Africa, the Straightfin Barb has disappeared from some areas, like the Uvongo River in KwaZulu-Natal, mainly due to invasive species. The Straightfin Barb may not be well known, but it plays an important role in aquatic food webs, and its decline is a warning sign that something’s wrong in our waterways.
What’s threatening it?
Invasive alien fish species
Pollution and habitat changes
Wetland destruction and altered water flow
Marico Barb (Enteromius motebensis)
A small freshwater fish found mainly in slow-flowing pools and shallow sections of small streams in the upper catchments of the Marico, Elands, and Crocodile (West) Rivers. It prefers vegetated banks and clear waters. While still found in about 20 locations, many face serious threats that could impact its survival. Protecting stream flow, habitat quality, and preventing alien fish introductions are key to conserving this species.
What’s threatening it?
Water abstraction linked to agriculture and urban use
Pollution from urban runoff and mine seepage through dolomitic groundwater
Habitat degradation from land use changes
Invasive predatory fish like Largemouth Bass
Recent severe droughts causing habitat fluctuations
Shortspine Suckermouth (Chiloglanis pretoriae)
The Shortspine Suckermouth is a bottom-dwelling fish found primarily in fast-flowing, rocky sections of rivers, such as riffles and at the bases of waterfalls. It is endemic to parts of the Crocodile and Pienaars River systems in Gauteng and is not often seen due to its specific habitat requirements and sensitivity. This species is widespread in upper catchments from the Incomati River in South Africa northwards into the Limpopo River in southern Zimbabwe. In suitable habitats, it is usually abundant. However, in some areas around Johannesburg and Pretoria, including its type locality, it appears to have been extirpated, likely due to pollution and altered water flow caused by industrial and urban development.
What’s threatening it?
Sediment buildup from upstream development and land use changes
Flow reductions caused by dams and water abstraction
Pollution from chemicals and sewage entering waterways
Habitat degradation due to human settlement and industrial activities
Large-scale Yellowfish (Labeobarbus marequensis)
A powerful, long-lived fish occurring in Gauteng, North West, Limpopo, and Mpumalanga provinces, extending into KwaZulu-Natal, reaching as far south as the Pongolo River. It prefers flowing, clear rivers with gravel or sandy bottoms. Though widespread, it is never abundant, as it sits high in the aquatic food chain. Large-scale Yellowfish grow slowly, mature late, and have low reproductive output, making them especially vulnerable to habitat decline. Although still found across a wide range, their numbers are decreasing. Conservation efforts include strict catch-and-release regulations and their protection under South Africa’s TOPS list.
What’s threatening it?
Water pollution, untreated sewage, and eutrophication
Destruction and siltation of spawning beds
River fragmentation by dams and weirs
Climate change and severe droughts reducing natural flow
Overharvesting in deep pools during drought periods
Spread of invasive species like Carp and Grass Carp
Possible hybridization with Smallmouth Yellowfish
Bulldogs (Marcusenius Spp.)
Bulldogs are strange, fascinating, electric-sensing fish found in slow to moderately flowing rivers across parts of southern Africa. They favor shallow channels, undercut banks, reed beds, and root tangles, especially in turbid water under 1.5 m deep. Some species are social and swim in loose groups, often hiding by day and active at night. While some species like M. pongolensis are relatively widespread, others such as M. caudisquamatus are highly restricted and considered Endangered. Ongoing taxonomic uncertainty suggests there may be cryptic species yet to be fully described, highlighting the need for more research, field surveys, and habitat protection efforts across their range. Bulldogs are indicators of river health and deserve more attention in freshwater conservation work.
What’s threatening them?
Habitat degradation from pollution, bulldozing, and erosion
Eutrophication and the spread of invasive alien plants
Industrial and agricultural runoff, especially in upper catchments
River modification (weirs, dams) and water quality decline
Limited range and population isolation in some species
Aquarium trade
African Longfin Eel (Anguilla mossambica)
An elusive, snake-like fish with a mysterious life cycle, the African Longfin Eel is born in the open ocean and arrives in rivers as a transparent "glass eel." It grows into a yellowish adult in freshwater, eventually transforming into a silver-bodied migratory form before returning to the sea to spawn and die, a round-trip journey of over 1,000 km. Remarkably, individuals may spend more than 40 years in rivers and streams before beginning this final migration.
As a top predator, this eel plays a vital role in river ecosystems, helping to maintain balance in aquatic food webs. It also holds cultural significance in parts of southern Africa, featuring in folklore and oral traditions. Due to its long and complex life cycle across ocean, estuary, and river systems, it is vulnerable to threats in all three realms and is currently listed as Near Threatened. Considered an "umbrella species," protecting the African Longfin Eel helps conserve the broader health of freshwater ecosystems.
What’s threatening it?
Barriers like dams and weirs block migration
Pollution, erosion and poor catchment management
Flow disruption from water abstraction
iNaturalist is a free, community-driven platform that allows anyone to record and share observations of plants, animals, and other organisms. Users simply take a photo, upload it with the location, and the global community of experts and enthusiasts helps identify the species. Verified observations contribute to biodiversity databases used by scientists and conservationists worldwide. Visit iNaturalist's website to learn more!
References:
Thank you for the use of the photos!
https://www.inaturalist.org/observations/36319158 https://www.inaturalist.org/observations/173805557
https://www.inaturalist.org/observations/44358543 https://www.fosaf.org.za/guide-yellowfish.php Research drawn from various articles on https://speciesstatus.sanbi.org/
Research drawn from various observations on https://www.inaturalist.org/
Straightfin barb (Enteromius paludinosus) photo https://en.wikipedia.org/wiki/Straightfin_barb
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