Mysterious holes are now ‘a common sight’ on Florida riverbanks. What’s causing it?

Sizable holes — or burrows — are appearing along Florida’s riverbanks, and it’s not the work of anything native to the state, experts say.

In some places, the pits are so numerous, the shoreline is taking on a musty Swiss cheese appearance.

What’s causing them? It’s an unwanted fish, the Florida Fish and Wildlife Conservation Commission says.

“These holes have become a common sight for our freshwater fisheries biologists,” the FWC’s Fish and Wildlife Research Institute wrote in an Oct. 18 Facebook post.

“Dug by the exotic and invasive armored sailfin catfish (aka ‘plecos’ or ‘Plecostomus’), these burrows serve as nesting sites where the catfish protect their eggs and young.”

The nests become visible when water levels drop.

Biologists say the digging is causing a range of problems for Florida’s freshwater ecosystems, destabilizing riverbanks, contributing to erosion and giving waterways a cloudy appearance.

Armored sailfin catfish are native to South America, but spread to Florida in the 1950s via the aquarium fish trade, experts say.

They can reach 22 inches in length and are notorious for uprooting plants and disrupting the food chain for native species, experts say.

“These hardy invaders face few threats in Florida, as they tolerate moderate salinity, gulp air when dissolved oxygen is low, and build burrows that allow them to withstand cold and drought,” the University of Florida’s Institute of Food and Agricultural Sciences reports.

“In addition, the spiny dorsal fins of these fish also pose a mortal danger to endangered, fish-eating birds.”

This story was originally published October 21, 2024 at 5:54 AM with the headline "Mysterious holes are now ‘a common sight’ on Florida riverbanks. What’s causing it?."