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University of Louisville Professor talks about the importance of Pacus to the Amazon Rainforest

Two hands hold and display a pacu, its scales dance between shades of a very dark green, with it getting lighter at the tail. the belly of the fish is orange and white, with this combination also being seen at the bottom of its head.
Tyler Howser
Oklahoma Department of Wildlife Services via AP
A native South American fish known as a pacu was caught in a southwestern Oklahoma lake in Caddo County. Game Warden Tyler Howser said the pacu is considered an invasive species and was destroyed.

Many may see Piranhas as a cornerstone of the Amazon rainforest, but special attention was brought to their more peaceful cousins during a recent presentation at Western Michigan University.

Though Pacus may be seen as uninteresting when compared to their world-famous relatives. University of Louisville Assistant Professor and Researcher Matt Kolmann is a fan, giving a presentation on Pacus Friday, Feb. 9.

He said these vegan piranhas play an important role as seed spreaders for the Amazon Rainforest.    

“They're really important to kind of the health and the maintenance of the rainforest," Kolmann said. "Studies have shown that by fishing out these species, we've actually impacted the health of those trees and plants too.”

The presentation also touched on the broader importance of fish in South America.

Kolmann said they not only plant much of the food in the area, but also culturally significant plants, like ayahuasca

“In some places, a quarter of the plants that live along the banks of the river are actually distributed, not by birds, or mammals, but by fish,” Kolmann said.

WMU Graduate Student Jonathan Kim attended the presentation.

He said he was surprised to learn that when it comes to the family that includes Pacus and Piranhas, Piranhas are the outlier.  

“I didn't really expect what the ancestral state of the family would be, which was eating fruits and plants,” Kim said.

Michael Symonds reports for WMUK through the Report for America national service program.

Report for America national service program corps member Michael Symonds joined WMUK’s staff in 2023. He covers the “rural meets metro” beat, reporting stories that link seemingly disparate parts of Southwest Michigan.