Defying Gravity: The Incredible Journey of Climbing Fish

The Unbelievable Observation at Luvilombo Falls

Seventeen years prior, Auguste Chocha Manda, a dedicated researcher from the Democratic Republic of Congo's Université de Lubumbashi, witnessed an astonishing spectacle at the Luvilombo waterfall. Thousands of minute shellear fish, a species scientifically known as Parakneria thysi, were seen actively ascending the sheer 50-foot rock face behind the cascading water. This sight was so improbable that, as Emmanuel Vreven, an ichthyologist from the Royal Museum for Central Africa in Belgium, notes, most people would consider such a claim absurd. Yet, this extraordinary phenomenon was indeed occurring, challenging conventional understanding of fish capabilities.

From Anecdote to Scientific Documentation: The Quest for Evidence

Despite Manda's initial observation and even a lost video recording, concrete scientific evidence of this unique behavior remained elusive for years. Pacifique Kiwele Mutambala, then a Master's student and now a PhD candidate at the Université de Lubumbashi, took on the challenge of documenting this incredible event. His perseverance led to a groundbreaking paper published in Scientific Reports, co-authored with Vreven and posthumously crediting Manda. This publication provides a detailed account of the shellear's unique traits and behaviors that allow them to ascend waterfalls, earning praise from experts like Steven Cooke, a fish ecologist, who likened their feat to a salmon climbing the CN Tower.

Unraveling the Secrets of Fish Ascending Waterfalls

Mutambala spent several rainy seasons immersed in the boisterous environment of Luvilombo Falls, meticulously observing the shellear fish's climbing actions. He noted that only smaller fish, typically a couple of inches in length, successfully made the ascent, suggesting that larger individuals become too heavy to counteract gravity and the water's force. The fish strategically chose the splash zones at the sides of the waterfall, avoiding the most powerful currents. Mutambala's dedicated filming, often leaving him completely soaked, captured the essential footage for their research.

The Anatomical Wonders Enabling Vertical Movement

Through detailed video analysis and CT scans, the research team uncovered the biomechanical marvels behind the shellear's climbing prowess. Their rear pelvic fins provide crucial support, while their front pectoral fins are equipped with microscopic, Velcro-like hooks that allow them to grip the rocky surface. A robust pectoral girdle provides the necessary muscular support for this strenuous activity. The fish employ rapid lateral undulations, resembling vertical swimming, a movement termed a "power burst." These bursts are interspersed with periods of rest on flat surfaces, conserving energy for the arduous, approximately ten-hour journey upwards. Despite their resilience, some fish inevitably fall, only to recommence their challenging climb.

Conservation Implications of a Vertical Migration

Beyond scientific curiosity, the study of shellear fish carries significant implications for the biodiversity and conservation of the region. The scientists hypothesize that these waterfall ascents are part of a critical upstream migration. If this migratory route is disrupted, for example, by diverting water for dams or irrigation, the shellear population could face severe threats. Vreven emphasizes that without water, there are no fish. Steven Cooke highlights that migratory fish species are disproportionately vulnerable to endangerment or extinction, underscoring the vital need to protect their entire habitat, including these extraordinary waterfalls. While the exact reasons for this vertical migration—perhaps better food sources or reduced predation upstream—are still under investigation, this research marks the first formal documentation of such behavior on the African continent, emphasizing its importance for both scientific understanding and conservation efforts.