For the first time, scientists have filmed thousands of bumblebee catfish (Rhyacoglanis paranensis) performing an extraordinary feat: climbing waterfalls in Brazil’s Aquidauana River. The footage, captured in late 2024, reveals the small fish using their fins, tails, and even suction-like movements to scale vertical rock walls up to four meters high.

Researchers believe this spectacle is tied to the rainy season and may be part of the species’ upstream migration for spawning. Both male and female catfish were spotted in the climbing groups, suggesting reproduction as the driving force.

During the most intense moments, the fish piled on top of one another, forming wriggling masses that fought against rushing water. Scientists say this behavior highlights not only the species’ resilience but also the importance of preserving natural river flows in the face of damming and habitat disruption.

These findings shine light on a poorly understood species and underscore why direct field observations remain vital for uncovering the hidden strategies wildlife use to survive.