Monster goldfish have been found in Lake Tahoe, and as benign as that sounds, researchers say the creatures could pose a threat to the other aquatic life there.

While looking for invasive wildlife in the lake, researcher Christine Ngai was part of a team who found the monstrous fish on a routine scan of the waters. She says they were surprised by the find.

“You just see this bright golden orange thing starting to float up, and you’re like, “What is that?” And then you take a net and scoop it up and it’s like, “It’s a goldfish!” Ngai said.

The fish, experts say, were most likely dumped there from aquariums; it’s a growing problem across the nation that has seen numerous species native to their environments put in danger as they’re consumed by the goldfish.

Despite the extreme cold temperatures of the lake, the goldfish are not only surviving in their new environment, they are actually breeding in it. This could also be a problem, because goldfish excrete certain nutrients that cause bacteria to murk up the water–not good for a tourist attraction.

“Oftentimes people think, ‘Well, gee, if I just dumped in one fish, that’s not going to make a difference,'” Pamela Schofield, an ecologist at the U.S. Geological Survey, said. “But it can with goldfish because of the way they eat — they root around in the sediment and that suspends the sediment up in the water.”

In short, don’t dump your fish. It’s suggested that if you want to get rid of some, get in touch with the local wildlife authority.