A Stunning Sight in Mato Grosso do Sul
The phenomenon was first spotted by the Environmental Military Police of Mato Grosso do Sul State in November 2024, at the Aquidauana River, part of the Paraguay River basin. They observed thousands of catfish scaling slippery rocks between 1 and 4 meters high, just behind the Sossego waterfall.
Within a week, Brazilian researchers rushed to the site and recorded the event—revealing unique insights into the migration and climbing abilities of this elusive fish.
How Do Catfish Climb Waterfalls?
Researchers discovered that climbing behavior in Rhyacoglanis paranensis varies depending on the time of day:
- Afternoons: The fish hid under rocks and shaded areas to avoid the heat.
- Evenings: As the sun set, the catfish began climbing in large groups.
The fish use a combination of wide fin positioning, lateral body movements, and powerful tail thrusts to push themselves forward. Scientists also believe they use a suction mechanism that allows them to grip smooth rock surfaces while climbing.
Why Do Catfish Climb?
The exact reason for this rocky ascent remains a mystery. However, scientists suspect that the behavior is linked to upstream migration for reproduction.
- Both male and female adults were observed.
- The climbing began at the start of the rainy season, a time when many Neotropical fish species migrate.
This suggests that the waterfalls are not just an obstacle but part of the natural breeding journey for this species.
Conservation Importance
The bumblebee catfish is a rare and poorly studied species, often found in fast-flowing rivers that make scientific observation difficult. Alongside them, other species—including Hypostomus khimaera and Ancistrus sp.—were also seen climbing the waterfall.
Scientists emphasize that this finding highlights the need for stronger conservation strategies, especially with growing threats like river damming, habitat fragmentation, and climate change.
“These findings highlight the importance of field observations in understanding small migratory fishes’ ecological role and conservation needs,” the authors write in the study.
What’s Next for Research?
To fully understand the climbing mechanism and migratory patterns of this catfish, more field studies during specific seasons are needed. By unlocking these secrets, scientists hope to better protect freshwater biodiversity and preserve river ecosystems under human pressure.
Study Reference
📖 Research Paper:
Manoela M. F. Marinho et al. (2025). Bumblebee on the rocks: Massive aggregation, migratory and climbing behaviour of a small Neotropical catfish. Journal of Fish Biology. DOI: 10.1111/jfb.70158
🌍 Key Takeaways
- Rare bumblebee catfish filmed climbing waterfalls in Brazil for the first time.
- Behavior likely linked to seasonal upstream migration for reproduction.
- Discovery sheds light on unique survival strategies in freshwater fish.
- Findings raise urgent conservation concerns due to river dams and habitat loss.