Goldfish are invading Lake Tahoe in the Sierra Nevada, amid concerns that the invasive species may affect the lake's ecosystem.

A team of researchers at the University of California at Davis, the University of Nevada at Reno, and the fish and wildlife departments of both California and Nevada started an annual survey of the lake in 2006 and revealed the presence of goldfish in it.  

The research team started a project in 2011 to reduce the number of goldfish and other species invading the nation's second-deepest lake. They used a technique called "electrofishing", where they dangled metal wires from the bottom of a boat to astonish the fish with electrical current. They captured the fish once they floated to the surface. The fish were sorted out to remove the invasive species and release the native species back into the lake, reports Reuters.

While searching for the invasive fish, the researchers nabbed a giant goldfish that was nearly 1.5 feet long and weighed 4.2 pounds. "During these surveys, we've found a nice corner where there's about 15 other goldfish," environmental scientist Sudeep Chandra of the University of Nevada, Reno, told LiveScience. "It's an indication that they were schooling and spawning."

Despite the team's efforts to get rid of the goldfish from the lake, the species have multiplied in numbers. Researchers are concerned about the invasion of the goldfish in Lake Tahoe, as the marine animal is one of the most destructive non-indigenous species in North America.

Speaking at a conference in New Orleans, researcher Chandra described the impact of goldfish invasion on the lake's ecosystem. He said that the goldfish preys on native animals and added, "they also excrete nutrients that are kind of in the ratio of Miracle Gro." It triggers an algal bloom which affects the crystalline waters, according to a report by the Los Angeles Times.

Besides the goldfish, other species invading the lake are tropical fish, seaweed and snails. Researchers think the invasive species might have ended up in the lake as a result of aquarium dumping. Aquarium owners dump unwanted fish and other animals owing to factors like size and aggressiveness of the fish.