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Invasive fish

Invasive fish, typically found in home aquariums, discovered in Georgia creek

Wes Gerrin is no stranger to fish.

As a master’s student and technician in aquatics labs at the University of Georgia Warnell School of Forestry and Natural Resources, Gerrin has seen his fair share of shiners and darters. But recently, as he looked into a bucket of fish he and colleagues collected from an Athens-area stream for a research project, he was stumped.

“We were trying to do a community assessment, and the overall goal was to see if we could find Altamaha shiners; they only exist in a relatively small range, and it was one of the things we were interested in,” said Gerrin. “So, I have all this fish in a bucket, and I put one in a photo tank and I’m like, ‘I don’t know what this is.’”

Turns out, the long gray fish with short fins and a stubby nose shouldn’t have been in the stream at all. It’s a weather loach, and the east Asian fish is more commonly seen in home aquariums—not natural waterways in North America. While it’s been spotted in the wild in California, New York and Alabama, it’s never been found in Georgia—until now.

Gerrin sent a photo of the fish to Warnell aquatic sciences associate professor Jay Shelton, who recognized and identified the fish. All told, the researchers collected 15 weather loaches from the creek, located upstream from the Oconee River. Now, UGA scientists are working with the Georgia Department of Natural Resources to assess if more are out there, posing a potential threat to native fish.

The main question now, says Georgia DNR biologist Brett Albanese, is how many are out in the wild and how far they have traveled. Albanese said DNR will be working with Warnell to assess additional places along the creek to determine the extent of the issue.

The discovery of the fish happened purely by chance. Gerrin, Warnell undergraduate student Jordan Horvieth and other researchers were in the area to work on Horvieth’s project that assessed the fish and wildlife resources on a particular parcel of land. The process involves a sampling method known as electrofishing, where an electrical current placed in the water directs fish to a certain area, where they can be collected, identified and released. The process does not harm the fish.

The discovery adds an interesting wrinkle to Horvieth’s project. While she entered it looking at the balance of wildlife on the property, it has turned into an exercise in managing for an exotic species. “If we’re trying to keep all of the ecological parts of this property in harmony, we can say, ‘If you want everything to be in harmony, you’re going to want to get rid of this species, because it will outcompete the natives,’” said Horvieth. “So, we’ll prescribe certain methods by which the landowner can attempt to eradicate the species.”

The fish were discovered near an area of the creek that is frequented by the public, and Shelton suspects that area may also be the point of origin for the fish.

“That was a lot of exotic fish that were found in about an hour,” said Shelton. “Now, we’re going to do a much more extensive survey and try and remove as many as possible. The concern is, if they get into the Oconee River, they can get anywhere—there’s no stopping them.”

Weather loaches are omnivores, which means they will be competing with native fish for the same food sources—and may also eat native fish eggs. And because they burrow into the river substrate, they may also destroy native fish habitat. But still, little research has been done on the fish, and so its overall effects are fairly unknown.

Still, Albanese said, one thing is for certain: They make it more difficult for native fish.

“Whenever predatory fishes are introduced, they tend to have much more harmful impacts on native species,” he said. The greater takeaway, he added, is for exotic aquarium fish to stay in their tanks—and out of natural rivers and lakes.

“Don’t release you fish,” Albanese added. “We don’t really know about the weather loach’s ecological impacts, but we have enough stressors in the aquatic system—we don’t need new ones.”


Associated Personnel:

Dr. James Shelton


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