Shellear Fish: The Remarkable Climbers of Luvilombo Falls

For over 50 years, tales of the shellear fish (Parakneria thysi) climbing waterfalls have circulated in the Democratic Republic of the Congo (DRC). Recent research led by Pacifique Kiwele Mutambala from the University of Lubumbashi and Emmanuel Vreven from the Royal Museum for Central Africa has confirmed these claims through extensive documentation. The team filmed thousands of shellear fish ascending the Luvilombo Falls in Upemba National Park during the rainy season, specifically between April and May, marking the first scientific evidence of this behavior.

For 50 years, there have been rumours of these fish climbing waterfalls. Scientists just filmed them doing it for the first timePopular ScienceZME Science

The shellear fish, measuring between 1.4 to 1.9 inches long, utilize their uniquely adapted pectoral and pelvic fins, which feature tiny hook-like projections known as unculi, to grip the vertical rock face. They propel themselves upward by wiggling their bodies, a process that takes approximately nine hours and 45 minutes to ascend the nearly 50-foot waterfall. This ascent includes only about 15 minutes of active climbing, with the remainder spent resting—often on horizontal ledges where they can recuperate for extended periods.

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Despite their adaptations, the climb is fraught with danger. Fish can lose their grip and fall due to sudden jets of water, particularly when navigating overhanging cliffs. The climbing behavior is believed to be a survival strategy, allowing the fish to return to upstream habitats after being washed downstream or to escape predators such as the silver butter catfish (Schilbe intermedius).

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The Luvilombo River ecosystem faces significant threats from human activities. Illegal fishing practices, particularly the use of mosquito nets, pose a direct risk to the shellear population during their climbing season. Additionally, agricultural practices upstream, including the diversion of river water for irrigation, threaten the ecological continuity of the river, potentially leading to the local extinction of the shellear fish.

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The researchers emphasize the need for conservation efforts to protect the shellear and its habitat. They advocate for the designation of Luvilombo Falls as a natural monument or an ecosystem of national interest. Such measures could not only help preserve the unique climbing fish but also promote ecotourism, shifting the focus from larger wildlife to these remarkable aquatic climbers. As Vreven notes, “There are amazing things to see in little fish,” highlighting the potential for increased awareness and protection of lesser-known species.

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• “The ability of shellears to climb waterfalls has been known anecdotally for over 50 years,” — Pacifique Kiwele Mutambala, Researcher

For 50 years, there have been rumours of these fish climbing waterfalls. Scientists just filmed them doing it for the first time

• “This could be made possible by paying more focused attention to these falls and identifying them as a natural monument and/or ecosystem of national interest.” — Study Authors

For 50 years, there have been rumours of these fish climbing waterfalls. Scientists just filmed them doing it for the first time

The shellear fish's extraordinary climbing ability not only captivates researchers but also underscores the importance of protecting fragile ecosystems. As human activities increasingly threaten their habitat, immediate conservation actions are essential to ensure the survival of this unique species.

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