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A twee tale of a fynbos fish on the brink

While watching a short film about fish, water flow and farming in the greater Cederberg area, I learnt about a curious little freshwater fish with the word ‘twee’ in its name. I became intrigued as to why the Twee River redfin was featured in this 12-minute film.

The use of ‘twee’, the Afrikaans word for two, also made me think of the word’s English meaning of being cute or quaint, or sometimes overly sentimental. It’s an old-fashioned word, not one I use. Yet now, this word – and this little fish – had lodged themselves in my mind.

So, I did what most curious people would do: I started googling…

The endemic Twee River redfin grows to 12 cm, the distance between an out-stretched thumb and index finger.
© Jeremy Shelton
The endemic Twee River redfin grows to 12 cm, the distance between an out-stretched thumb and index finger.
What’s in a name?

The fish’s full name – Twee River redfin – holds the clue as to where this fish comes from.

I read up on the Twee River catchment: a subcatchment of the Olifants and Doring Rivers, close to Ceres and Clanwilliam respectively, deep within the Cederberg mountains of the Western Cape.

This area is also well within the fynbos treasure chest of the Cape Floral Kingdom.

The Twee River is a subcatchment of the Olifants-Doring catchment in the Western Cape.
© Dean Impson
The Twee River is a subcatchment of the Olifants-Doring catchment in the Western Cape.
Drama below the water line

It dawned on me that beyond the well-celebrated proteas, dancing sugarbirds and bright sunbirds of the fynbos realm, a range of ideally adapted, associated aquatic life also exists.

Many species are found only in one specific location. And when that location is a river, I realised, the risks of drought, low-water levels and other climate-change impacts can be dire. Life threatening. Especially for this freshwater fish found only in one tributary.

< spoiler alert > This tale of the Twee River redfin is quite a sad story, because this small river fish is currently the most threatened freshwater fish in both the Cape Floral Kingdom and in South Africa.

Photographed here with a different species, the Breede River redfin, is freshwater scientist Jeremy Shelton who also worked on the Waterdak documentary.
© Steve Benjamin
Photographed here with a different species, the Breede River redfin, is freshwater scientist Jeremy Shelton who also worked on the Waterdak documentary.
A small fish in a small pond

The Twee River is the only place on earth that the Twee River redfin is found.

Deep pools of water are their preference. And amongst clumps of the indigenous river plant palmiet, these fynbos fish like to play and hide. I imagine it must be a quiet, peaceful life.

But over the years various threats have ruffled the river banks. The ploughing of the land for agriculture and the extraction of water for irrigation have taken their toll. Run-off from chemical fertilisers increases algal growth and decreases water quality. When combined with excessive water abstraction, water quality can worsen quickly. Not good for farmers, not good for fish.

Another looming threat which, if it were to happen, could wipe out this specific redfin forever: the introduction of invasive fish into the Twee River. Even other indigenous fish, such as the Cape kurper and Clanwilliam yellowfish, that have already been unwisely introduced into the Twee catchment are a threat to this critically endangered redfin.

This mountainous area with many rivers forms part of the Groot Winterhoek Water Source Area and is considered the ‘water roof’ of the Western Cape.
© Otto Whitehead
This mountainous area with many rivers forms part of the Groot Winterhoek Water Source Area and is considered the ‘water roof’ of the Western Cape.
A good twist in the tale

Due to its national importance for fish conservation, the Twee catchment has been declared a critical biodiversity area for fish conservation. There is also a land stewardship initiative to work with riparian landowners to secure habitat for this species. And furthermore, to protect this fish, fish scientists from CapeNature and the South African Aquatic Biodiversity Institute have stocked some Twee River redfin in farm dams to create refuge populations.

Public awareness for local landowners is an essential part in this species’ future. Released at the end of 2021, the 12-minute short film titled Waterdak tells the story of this fish, local water flow and a few fruit farmers of the Koue Bokkeveld. At over 1000m above the Ceres Valley, these Cape landowners have experienced the impacts of farming with limited water.

Just like a roof channels water into a rainwater tank, so the Koue Bokkeveld mountains – the ‘waterdak’ of the Western Cape – channel the rain and snow melt from the mountain peaks into rivers that provide water for aquatic ecosystems and for growing the fresh produce that we all eat.

With funding support from WWF and the fastidious work and dedication of freshwater scientists who research and monitor the health of river systems, we now have a water film and a dataset on river flow and vital aquatic biodiversity. We meet a few of these individuals in this short doccie.

As a freshwater ecologist, Dr Bruce Paxton – of the Freshwater Research Centre – has been working in the Koue Bokkeveld for close on a decade thanks to funding from the Hans Hoheisen Charitable Trust, the Water Research Commission and WWF. I learnt that the aim of the data collection and research is to balance the needs of water for farmers and water for redfins.

I was pleased to learn that later this year, WWF in partnership with the Freshwater Research Centre will undertake a population survey of historical sampling sites to assess the status of Twee River redfin populations in comparison to previous years. Bruce explained that this information will then feed into management plans for the river to ensure the continued survival of this special little fish.

Dr Bruce Paxton has been working in the Koue Bokkeveld for a decade to measure water flows and monitor the redfins
© Jeremy Shelton
Dr Bruce Paxton has been working in the Koue Bokkeveld for a decade to measure water flows and monitor the redfins
Too twee or not too twee?

Perhaps I’ve become overly sentimental about a small fish that, until recently, I didn’t know anything about. That our shared freshwater comes from the rivers – from nature – should not be forgotten. Nor should the twee tale of this native fish found in a tiny tributary in a corner of the Cederberg.

From all the facts and a potential future trajectory that I’ve uncovered about this little fish, it’s quite a twee-less realisation that the science shows that unless appropriate coordinated action is taken, the Twee River redfin may become the first freshwater fish species in South Africa to become extinct.

While there is enough to get depressed about, and the world has bigger fish to fry, I am heartened by what is already happening in the waters of the Twee River catchment. The golden triangle of good science, awareness of a healthy river system and working with committed landowners will hopefully secure a future for this redfin species. And while it is likely not the sole focus or incentive for local farmers to take action, the Twee River redfin is a very cute poster child for why healthy rivers really matter.

Sue Ras
Sue Northam-Ras , Communications Manager: Environmental Programmes

Sue believes in making information valuable by writing and shaping content in a way that gives it meaning. She packages the environmental content for WWF South Africa.

Learn more

For the fish-curious, time-tight viewers: watch five minutes in for the fascinating lifecycle of the redfin.