For over 50 years, people in Central Africa have shared stories about tiny freshwater fish called shellears. These fish were said to scale the rock faces behind waterfalls. Now, this behavior has been officially documented for the first time.
Images of shellear fish climbing up the rock face behind Luvilombo Falls P. Kiwele Mutambala et al., Scientific Reports, 2026 under CC-BY-4.0
Videos and photos now confirm these rock-climbing fish. They show their journey up the 50-foot Luvilombo Falls in the upper Congo Basin. A new study also describes how they achieve this amazing feat.
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Start Your News DetoxThe findings were published on April 2 in Scientific Reports. They are important for conservation in the region. The shellears' migration makes them vulnerable to habitat loss and illegal fishing.
Pacifique Kiwele Mutambala, a study co-author, shared his thoughts. He is an ichthyologist at the University of Lubumbashi in the Democratic Republic of the Congo (DRC). He told Reuters that it's incredible to see fish climb waterfalls. He noted it shows wonders exist that are beyond our imagination.
How Shellears Climb Waterfalls
Researchers have seen rock-climbing fish in other parts of the world. These include South America, Asia, and Australia. However, this behavior had never been seen in Africa before.
Seventeen years ago, Auguste Chocha Manda, another study co-author, filmed thousands of shellears. These fish, Parakneria thysi, were climbing Luvilombo Falls in the DRC. Unfortunately, he lost the footage.
So, the team returned to observe the fish. They watched them at the end of the rainy season in the spring of 2018 and 2020. The fish mostly climbed the waterfall during big floods. Their migration was busiest in mid-April.
The creatures use tiny, hook-like structures on their fins to grip the rocks. Then, they wiggle their tails to push themselves upward. Kiwele Mutambala told Scientific American it's like the fish are swimming vertically.
The journey is tough and involves many breaks. The fish move upward in short bursts. Then they rest for 15 seconds to over an hour. The team estimates the full climb takes about ten hours.
Many fish fall and have to restart their climb. Only fish under two inches long were seen climbing. Larger ones become too heavy, according to Emmanuel Vreven. He is a study co-author and ichthyologist at the Royal Museum for Central Africa in Belgium.
Why This Discovery Matters
Scientists are not sure why these fish are such brave adventurers. They might climb to escape predators or find more food. They could also be looking for mates upstream.
Adam Summers, a biologist at the University of Washington, called it "fabulous." He was not involved in the study. He noted how the fish use "friction enhancers" to stick to the rocks and climb.
Understanding the fish's migration route is key to understanding the region's ecosystem. During the dry season, people sometimes divert water from Luvilombo Falls for irrigation. The fish gathering at the bottom of waterfalls also makes them easy targets for illegal fishing nets.
Kiwele Mutambala told Reuters that this discovery highlights the need to keep waterways connected. This is especially important in the Congo Basin, where fish behavior studies are rare.
Deep Dive & References
Thousands of small fish defy gravity to climb Congo waterfall - Reuters, 2026 See These Ziti-Sized Fish Scale a 50-Foot Waterfall - Scientific American, 2026 First record of waterfall climbing in Africa by the shellear Parakneria thysi (Teleostei: Kneriidae) - Scientific Reports, 2026
