What Is the Rock-Climbing Fish That Can Defy Gravity? Everything You Need to Know
A fish that is the size of a thick french fry can literally climb a 50-foot waterfall. Scientists have now proven it with video evidence, CT scans and years of fieldwork at the Luvilombo Falls in the Democratic Republic of the Congo.
The study provides the first scientific confirmation that Parakneria thysi, a small African freshwater fish, is capable of climbing near-vertical waterfall surfaces. The finding validates local accounts that scientists had been unable to confirm for nearly two decades.
How Rock-Climbing Fish Scale 50-Foot Waterfalls
The fish rely on specialized anatomical adaptations to pull off the climb. Hook-like projections on their pectoral and pelvic fins function like Velcro, enabling them to grip slippery rock surfaces even under strong water current.
Their locomotion combines that fin-based adhesion with body undulation, allowing individuals to inch upward against both gravity and flowing water. Emmanuel Vreven, an ichthyologist at the Royal Museum for Central Africa in Belgium, described the movement, per NPR: “You see also the lateral undulations of the fish very fast. It’s as if they are swimming vertically.” The movement is called a power burst.
The process is remarkably energy-efficient. While the total journey can take 9 to 10 hours, the fish spend only about 15 minutes actively moving. “When they arrive at a flat surface,” Vreven says, “they will pause for a longer time. When they recover the energy, they can begin another step of the climbing. Most of the time is in fact resting.”
Researchers confirmed these mechanics through frame-by-frame video analysis and CT scanning. Only smaller individuals — generally under 48 mm — are able to complete the ascent. Larger fish are likely limited by their weight.
Why Thousands of Tiny Fish Climb Waterfalls in the Congo
This is not an isolated stunt. Researchers documented the fish ascending waterfalls up to approximately 15 meters high, often in groups numbering in the thousands. That pattern suggests the behavior represents a large-scale migratory strategy.
The climbing is closely tied to seasonal flooding, which can wash fish downstream and force a return to upstream habitats. By climbing waterfalls, the fish may avoid predators, reduce competition and access more favorable ecological conditions.
Despite their small size, the fish undertake an extraordinarily demanding climb that has been likened to a salmon scaling something as extreme as Niagara Falls or even the CN Tower. The ascent itself is risky — individuals can be dislodged by fast-moving water or struggle to navigate complex features such as overhangs, sometimes requiring inverted positioning.
What the Discovery Means for Science and Conservation
The findings emerged from fieldwork conducted between 2018 and 2020, but the story began about 17 years ago with long-standing rumors in Central Africa that tiny fish were somehow able to climb waterfalls. For decades, local accounts hinted at the behavior, but it remained largely anecdotal.
“If you would ask a regular person, do you think fish can climb falls, most of them will tell you: you are crazy,” Vreven said. “Well, it exists, it is out there.”
The study highlights a rare and extreme example of evolutionary adaptation, demonstrating how behavior and morphology can work together to enable survival in challenging environments. It also underscores broader conservation concerns. Migratory species like Parakneria thysi are particularly vulnerable to extinction, especially in the face of human activities such as overfishing and river modification.
This article was created by content specialists using various tools, including AI.
