Full of carp

Giant goldfish swimming in Lake Tahoe’s waters are a concern to scientists at the University of Nevada, Reno. Goldfish, a type of carp, are not native to Lake Tahoe, and biologists speculate that the population grew after people emptied aquariums into the lake. Pet goldfish are the most commonly dumped invasive species, according to a study conducted at the University of California, Davis.

A school of 15 large goldfish was discovered in a “corner” of Lake Tahoe, said UNR environmental scientist Sudeep Chandra. The presence of goldfish, all living in one place, indicated that the fish have been breeding. One goldfish is over a foot long and weighs 4 pounds.

An abundance of goldfish could threaten the native fish species in Lake Tahoe. Goldfish excrement also clouds up clear waters because it contains nutrients that contribute to “algae bloom.”

“It’s unclear whether the giant fish were introduced as fully grown adults, or while they were still small,” said Chandra in a Live Science report. “The goldfish are just one of several species of invasive warm-water fishes in Lake Tahoe. The invasion is resulting in the consumption of native species.”

Sue Williams, who led the UC Davis study, says that unwanted pet fish should be returned to pet shops instead of being flushed down the toilet or dumped in a local body of water. The Department of Fish and Wildlife can also advise pet owners—the Davis study found that “aggression” was the main reason people got rid of pet fish.