4 days ago
Thousands of catfish seen climbing waterfalls in Brazil for first time. See them
In a river near a police department in southern Brazil, thousands of catfish amassed at the base of a waterfall and began to climb. The unusual fish gathering caught the attention of police officers — and for good reason.
It turned out to be a first-of-its-kind sighting.
A department of the Environmental Military Police in Mato Grosso do Sul State contacted a team of scientists in November 'to report the occurrence of a massive aggregation of bumblebee catfishes' near their headquarters, according to a study published Aug. 8 in the peer-reviewed Journal of Fish Biology.
Intrigued, researchers visited the river near the headquarters and were stunned to find thousands of small catfish 'clustered and slowly moving upstream,' the study said. They watched for 20 hours as the fish climbed the waterfalls.
A video, shared by Fish in the News in an Aug. 9 Facebook post, shows the bumblebee catfish 'at night, climbing vertical rocky walls' along the edge of a waterfall, researchers said. The orange-and-black fish almost seem to wiggle their way upward, even as the angle of the wall becomes steeper.
In flatter areas, the fish 'aggregation was so massive that specimens were seen above each other, climbing the large cluster of fish,' the study said.
Another video, also shared by Fish in the News, shows the bumblebee catfish climbing over the top of a waterfall one at a time.
Researchers identified the vast majority of the fish as Rhyacoglanis paranensis, a species of bumblebee catfish, but also noticed a few individuals of three other fish species. In general, Rhyacoglanis catfish are 'relatively rare' and their lifestyle is 'virtually unknown.'
The sighting in Mato Grosso do Sul State was 'the first time' Rhyacoglanis paranensis catfish had been seen in a 'massive aggregation' and the first time the species had been seen climbing, the study said.
Based on dissections of a few catfish and the timing of the sighting, researchers concluded the bumblebee catfish were likely migrating upriver to spawn and were not eating during the migration.
'The migratory movements of smaller (fish) species remain largely unknown, mainly because these events occur briefly, under specific environmental conditions, and are challenging to detect in highly diverse ecosystems,' researchers said.
'Field observations, such as those in this study, provide valuable insights into the ecology of smaller fish species, representing most of the native ichthyofauna in South America,' the study said.
Mato Grosso do Sul is a state in southwestern Brazil and along the border with Bolivia and Paraguay.
The research team included Manoela Marinho, Eris de Paula, Francisco Severo-Neto, Yasmim Santos and Heriberto Gimênes-Junior.
