Gigantic goldfish have been found in the waters of Lake Tahoe. Researchers trawling the lake for invasive fish species scooped up a goldfish that was nearly 1.5 feet long and 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 said. "It's an indication that they were schooling and spawning." The arrival of the fish, which were probably dumped there by aquarium owners, goldfish are an invasive species that could interfere with Lake Tahoe's ecosystem.
It's unclear whether the giant fish were introduced as fully grown adults, or while they were still small, Chandra said. But even a small creature can have a big impact, if there are enough of them. 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," Chandra said. What's more, the invasive fish excrete nutrients that cause algal blooms, which threaten to muddy Tahoe's clear waters.
Aquarium dumping has become a common practice and it's taking a toll on native wildlife. A recent reporton California's aquarium trade found that fish owners and importers are introducing hardy, nonnative aquatic species to California waters. "Globally, the aquarium trade has contributed a third of the world's worst aquatic and invasive species," Williams, who was lead author of the report, said.
While the exact number of aquarium owners dumping fish is unknown, scientists know the practice is occurring because these species could not have ended up in these waters naturally. Between 20 percent and 69 percent of fish keepers surveyed in Texas admitted to dumping, according to Williams.
Other ways that invasive species find their way into natural ecosystems include aquaculture, live seafood, live bait and fishing and recreation vessels. More than 11 million nonnative marine organisms representing at least 102 species arrive at ports in San Francisco and Los Angeles alone, Williams has found.
The invaders include tropical fish, seaweed and snails. One of the deadly type of seaweed is known as Caulerpa. A type of algae that produces toxic compounds that kill off fish, Caulerpa was eradicated in 2000 (at great expense) from lagoons in Southern California.
Aquarium owners should be more careful when disposing of unwanted fish and other animals, Williams cautioned. "It's pretty simple: Don't dump your fish," she said. Instead, she suggests calling the pet shop that sold the fish or your state department of fish and wildlife.
The largest pet goldfish, as per reports available, was a fish named Goldie that was 15 inches (38 cm) long and weighed more than 2 pounds (0.9 kg).