Goldfish or Carassius autatus have been great household pets for generations. We thank them for that. Native to East and Central Asia, goldfish can live in a variety of habitats, adapt to poor water conditions and have a wide range of dietary options. While these characteristics may be helpful for the pet owner, the goldfishes' ability to adapt makes them highly invasive. When introduced to our watersheds, a variety of direct negative impacts follow.
How are goldfish ending up in local watersheds across the country you might ask? It is more common than one may think. This cute, lovable, pet lives approximately six to seven years but have been known to live up to 30. So what happens when a family moves or a child gets bored? Many times the fish is brought to a local pond and "released."
A study surveying 2,000 teachers in 10 states revealed that one in four teachers who utilize live animals in the classroom release the species in the wild many of which are invasive . Other means of introducing this invasive species include aquaculture, live seafood, live bait, fish vessels, forage and the aquarium trade.
Goldfish have been reported in every state excluding Alaska and maintain reproducing populations in at least 45 states. Many of us have heard about the recent discovery of more than 15 "gigantic goldfish" in Lake Tahoe this past February. These fish were 1.5 feet long and 4.2 pounds.
Goldfish when removed from the in-home tank cause harm to native species and ecosystems. For example, goldfish excrete nutrients that cause algal blooms and result in muddy water conditions. They also consume and compete with native species while taking a toll on native wildlife as a whole. This is why some places around the country are considering banning goldfish from pet stores, making it illegal to bring them in from other states, or are developing hotlines to report dump sightings.
So what can we do to ensure we don't end up with another invasive species in the foothills? Instead of "releasing" or dumping your pet goldfish outside in your local waterways, you can take them to your local pet stores. Additionally, teachers can contact the California Department of Fish and Wildlife to raise a trout in their classroom and later release it into an appropriate body of water. Schools can incorporate discussions about invasive species into their curriculums and we can share this information with our community.
Please feel free to contact the Chowchilla Fresno River Watershed Coordinator to learn what pet stores will accept returned goldfish in your area, to learn more about raising a trout in the classroom or to have us speak about this and/or other watershed related topics at your school or community group.
Brittany Dyer is the assistant watershed coordinator with the Central Sierra Watershed Committee Chowchilla / Fresno Rivers Watershed. email@example.com.