A breakthrough study from Walter Sisulu University in Mthatha, Eastern Cape, has revealed that Rooibos — one of South Africa’s most iconic crops — could hold the key to more sustainable and profitable fish farming. Researchers found that adding green Rooibos extract to tilapia feed improved growth rates and feed efficiency, a discovery with major implications for aquaculture across South Africa and beyond.
From Tea to Tilapia
Led by Prof Grace Okuthe, senior researcher at Walter Sisulu University’s Faculty of Natural Science, the trial compared conventional feed with feed enhanced by either fermented Rooibos (red) or unfermented green Rooibos. The results showed that tilapia fed green Rooibos grew nearly 3% faster and converted feed into body mass more efficiently. For fish farmers, even small percentage gains mean lower costs, quicker production cycles, and stronger competitiveness.
The team attributes the improvement to Rooibos’ bioactive compounds, which support gut health and nutrient absorption. Early signs of DNA protection were also detected, pointing to broader health benefits.
Economic and Environmental Potential
For aquaculture producers, better feed conversion means less waste entering water systems, reducing nutrient runoff and environmental risk. This aligns with growing global demand for sustainable production practices.
Equally important are the opportunities for Rooibos growers. Cultivated exclusively in the Western Cape, green Rooibos could see a surge in demand as a natural feed additive, creating new markets and supporting job creation in harvesting, processing, and logistics. By replacing some imported synthetic feed additives with a local product, South African farmers stand to cut input costs and strengthen supply chains.
“This research shows how an indigenous crop can open new economic pathways,” Prof Okuthe explained. “It combines heritage, science, and sustainability in a way that can benefit both aquaculture and rural communities.”
A National Opportunity
While the Rooibos plant grows only in the Western Cape, the benefits of this research extend far wider. Aquaculture is a fast-growing sector across South Africa — from tilapia farms in Limpopo and Mpumalanga to trout and catfish operations in the Free State, KwaZulu-Natal, and the Eastern Cape. A homegrown additive that improves efficiency and lowers costs offers direct opportunities to producers nationwide.
The next phase of research will test green Rooibos extract on other species such as shrimp and freshwater fish, potentially creating a universal natural additive with global appeal.
As aquaculture continues to supply more than half the world’s fish, South Africa has an opening to lead with innovation. By turning a traditional herbal tea into a modern farming solution, Rooibos could help chart a sustainable future for food security and agricultural growth.