Thousands of catfish filmed climbing rocks
A group of small catfish were filmed climbing rocks about 1-4 metres high in Brazil, a species never before recorded to climb rocks.
Bumblebee on the rocks: Massive aggregation, migratory and climbing behavior of a small Neotropical catfish - Marinho - Journal of Fish Biology - Wiley Online Library
Thousands of climbing catfish filmed waterfalls | Science | AAAS
https://www.science.org/content/article/thousands-climbing-catfish-filmed-scaling-waterfalls
In November 2024, an orange-and-black catfish was filmed climbing up rocks against the current in Rocedo, Brazil. A week later, a team of Brazilian researchers arrived to document the phenomenon and published a research paper.
Rock-climbing catfish spotted in Brazil - YouTube
The majority of these catfish were Rhyacoglanis paranensis, a species in the Pseudopimelodidae family. They are small, measuring just 89.2mm in length, and more than 1,000 individuals were observed in the area.
Shortly after arriving at the site, the researchers discovered that the catfish's climbing habits varied depending on the time of day: On hot afternoons, only a few catfish would wander around in the shade of rocks, but as the sun went down, a large number of catfish would emerge from a nearby pool of water and begin climbing up the rocks en masse.
Based on the catfish's climbing movements and the position of its fins, the researchers speculate that the catfish may create a small cavity under its belly, creating negative pressure and allowing it to attach to moist rocks, a mechanism known to exist in other catfish species.
On flat, horizontal rocks, they formed very large groups, with individuals seen climbing on top of each other.
A group of catfish climbing rocks - YouTube
There were few schooling catfish in the vertical sections, and most individuals were climbing alone.
Rock-climbing catfish climbs almost vertical cliffs - YouTube
They have also been observed climbing onto man-made objects such as plastic buckets.
Rock-climbing catfish also climbs buckets - YouTube
It's unclear why they were climbing, but the researchers speculate that they were probably climbing to spawn upstream. The researchers collected and observed 439 specimens, and found that most of them were mature adults. The rock-climbing observations also coincided with the time when other fish living in the same water system were migrating to spawn.
In addition, three other fish species were also spotted climbing the rocks alongside Rhyacoglanis paranensis. These four species have never been recorded climbing rocks before. 'This is the first reported observation of rock-climbing behavior and large-scale aggregations in a species of the Pseudopimelodidae family,' the researchers wrote.
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