Giant Goldfish Found In Lake Tahoe, Invasive Goldfish Likely Dumped In Fragile Ecosystem By Aquarium Owners

Monster goldfish, more than a foot long, have recently been found living in the fragile environment of Lake Tahoe. Including one individual that was 1.5 feet long and 4.2 lbs. The invasive and environmentally-destructive goldfish were likely originally dumped there by aquarium owners, before becoming established as they are now. Researchers note that the monster fish pose a significant threat to many of the native species in the lake, and will contribute to the rapidly decreasing clarity of the Lake Tahoe waters.


The invasive goldfish appear to be thriving in the lake, reproducing at a rapid rate. Scientists in the field warn that because of their ‘rooting’ behavior, feeding in the sediment, that they will contribute to the loss of clarity that the lake has been experiencing in recent years. The clarity of the lake has greatly decreased since the area was first settled, as a result of pollution, soil erosion, and massive deforestation.

“We know that we have a giant goldfish, the question now becomes how long has it been there and how many others are there in the lake?” said Dr Sudeep Chandra, an associate professor at the University of Nevada, Reno.

Aquarium dumping is a problem throughout the whole country, not just at Lake Tahoe, contributing to species extinctions, and disrupted ecosystems.

“Globally, the aquarium trade has contributed a third of the world’s worst aquatic and invasive species,” Sue Williams, an ecology professor at UC Davis, and the lead author of a recent report on the subject.

“Oftentimes people think, ‘Well, gee, if I just dumped in one fish, that’s not going to make a difference,'” Pamela Schofield, an ecologist at the U.S. Geological Survey is quoted as saying. “But it can with goldfish because of the way they eat — they root around in the sediment and that suspends the sediment up in the water.”

The primary issue is that when people decide that they no longer want a pet, they are still unwilling to let the animal die. But releasing the animals into the ‘wild’ simply causes problems for the other animals in the vicinity, whether through predation, disease, or resource competition. These invasive species can often lead to a significant collapse in the overall health of the system. Most of these problems seem to be, in my opinion, from the throw-away culture of pet ownership that currently seems prevalent. People often view their pets as a form of entertainment, or a product, and when they no longer are interested in them the animals become strays or end up at animal shelters. Or in the Everglades eating everything, for that matter.

“People have fish in their aquariums they don’t want to kill, so they dump them into a pond, river or spring. They may save the life of one fish, but in doing so they could wipe out a whole population of native fishes,” said Tim Bonner, assistant professor of biology at Texas State University, according to a 2006 Texas Parks & Wildlife Magazine report about the state’s aquarium dumping problem.

Some further background on goldfish:

“The goldfish (Carassius auratus auratus) is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish.”

“A relatively small member of the carp family (which also includes the koi carp and the crucian carp), the goldfish is a domesticated version of a less-colorful carp (Carassius auratus) native to east Asia. It was first domesticated in China more than a thousand years ago, and several distinct breeds have since been developed. Goldfish breeds vary greatly in size, body shape, fin configuration and coloration (various combinations of white, yellow, orange, red, brown, and black are known).”

“Behavior can vary widely both because goldfish live in a variety of environments, and because their behavior can be conditioned by their owners.”

“Goldfish have strong associative learning abilities, as well as social learning skills. In addition, their visual acuity allows them to distinguish between individual humans. Owners may notice that fish react favorably to them (swimming to the front of the glass, swimming rapidly around the tank, and going to the surface mouthing for food) while hiding when other people approach the tank. Over time, goldfish learn to associate their owners and other humans with food, often ‘begging’ for food whenever their owners approach.”

“Goldfish are gregarious, displaying schooling behavior, as well as displaying the same types of feeding behaviors. Goldfish may display similar behaviors when responding to their reflections in a mirror.”

“Goldfish that have constant visual contact with humans also stop considering them to be a threat. After being kept in a tank for several weeks, sometimes months, it becomes possible to feed a goldfish by hand without it shying away.”

“Goldfish have learned behaviors, both as groups and as individuals, that stem from native carp behavior. They are a generalist species with varied feeding, breeding, and predator avoidance behaviors that contribute to their success. As fish they can be described as ‘friendly’ towards each other. Very rarely does a goldfish harm another goldfish, nor do the males harm the females during breeding. The only real threat that goldfish present to each other is competing for food. Commons, comets, and other faster varieties can easily eat all the food during a feeding before fancy varieties can reach it. This can lead to stunted growth or possible starvation of fancier varieties when they are kept in a pond with their single-tailed brethren. As a result, care should be taken to combine only breeds with similar body type and swim characteristics.”

Source: Huffington Post and Wikipedia

Image Credits: Heather Segale/University of Nevada, Reno

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