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Giant Goldfish One of Several Trespassers in Lake Tahoe


Story at-a-glance -

  • Researchers checking for invasive fish species in Lake Tahoe have discovered not only goldfish, but gargantuan goldfish as well.
  • Goldfish and other warm-water fish in the lake present a problem because these invasive species threaten Tahoe’s ecosystem.
  • Goldfish and other similar invaders are dumped into the lake by aquarium owners. Other invasive species wind up there as the result of aquaculture, live seafood and bait, and fishing and recreational boats.
  • If you’re an aquarium owner, you should never dump fish in lakes. Instead, call the store where you bought the fish or your state department of fish and wildlife. Boaters should remove all aquatic plants and animals from vessels.

By Dr. Becker

It may not be as mysterious as Scotland’s notorious Loch Ness Monster, but Lake Tahoe is home to a “monster” as well – gigantic goldfish.

In 2011, researchers from the University of Nevada, Reno were checking the lake for invasive fish species and captured an XXL goldfish that measured a foot and a half long and weighed a whopping four pounds, two ounces.

Invasive Warm-Water Fish Threaten Lake Tahoe Ecosystem

Scientists have discovered an area of the lake where approximately 15 other goldfish reside. According to Dr. Sudeep Chandra of UNR, the finding indicates the goldfish are schooling and spawning. Chandra believes aquarium owners probably dumped the fish in the lake. Their presence is a problem because goldfish are an invasive species that could disrupt Lake Tahoe’s ecosystem.

Goldfish are one of several types of invasive warm-water fish present in Lake Tahoe. The problem with invasive species is not only that they eat native species, they also expel substances that cause algae to proliferate, creating cloudiness in Tahoe’s renowned clear waters.

Aquarium dumping is a common problem in the U.S. and other countries, and Lake Tahoe officials have been battling the situation for years. In addition to goldfish, other invasive species have also been discovered in the lake, including bluegill, crappie, largemouth bass, tropical fish, snails and seaweed.

And aquarium dumping is certainly not the only way non-native fish invade Tahoe and other natural ecosystems. Other sources of introduction include aquaculture (farming of aquatic organisms), live seafood and bait, and fishing and recreational boats.

How You Can Help

Susan Williams, an evolution and ecology professor with the University of California, Davis Bodega Marine Laboratory, says studies of aquarium dumping suggest that size and aggressiveness of fish are the two main factors involved when an aquarium owner decides to “relocate” a pet to another body of water.

The solution? According to Williams, “It’s pretty simple: Don’t dump your fish.” She suggests calling the store that sold the fish or your state department of fish and wildlife. Euthanasia is an option if all other possibilities have been exhausted. What should never be an option is flushing fish down the toilet.

A 2010 bulletin produced by UNR and UC Davis offers the following additional suggestions for boaters, aquarium owners, and visitors to Lake Tahoe:

  • Remove all aquatic plants and animals from boats and transported gear.
  • Do not release aquarium pets, plants or live bait into aquatic ecosystems.
  • Do not move live fish and other aquatic organisms from one water body to another.
  • Report nonnative species.

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