Goldfish have invaded a picturesque storm pond in Red Deer’s Anders neighbourhood.
The City of Red Deer said a goldfish population has made itself at home in the pond and needs to be removed to protect the environment.
Goldfish are considered a non-native invasive species that pose a threat to natural aquatic ecosystems and native fish species in the Red Deer River.
“Removing invasive species will help to ensure that we maintain the aquatic health of our stormwater system and local waterways,” said city environmental services manager Tim Ainscough.
“The Anders pond connects directly to our stormwater system and to the Red Deer River. Anything that is dumped in local storm ponds or storm drains will flow directly into our stormwater system and into the Red Deer River.”
The fish likely got into the pond by being dumped directly into the water or by being put down stormwater drains.
The city will begin removing the goldfish Sept. 9 and expects to be at it until about Oct. 21. A specialist will be called in to kill the goldfish with an organic compound derived from plants called Rotenone. Two applications will be done six-weeks apart.
Rotenone is highly toxic to all species of fish, but moderately toxic to birds, mammals, amphibians and invertebrates.
September was chosen because amphibians have passed the larval stage and bird breeding and nesting periods have ended.
Eating a dead goldfish or drinking the pond water would have little effect on a bird, says the city. To get a lethal dose, a small bird would have to drink 95 litres of water and 18 kilograms of fish in a day, far above a typical daily diet of six millilitres of water and nine grams of food.
Levels of toxicity are low enough that animals, including pets, will not be harmed, says the city. However, as a precaution, the pond will be fenced off while goldfish removal is underway.
Sunlight breaks down Rotenone within two weeks and there will be no permanent impact on the pond.
Goldfish — or Prussian carp, a form of wild goldfish — can cause all sorts of problems in the environment. They compete with native species for food and habitat and can introduce diseases and parasites, all of which can reduce biodiversity.
They also stir up sediments and nutrients, clouding the water and causing more algae and plant growth.
Facing no natural predators in this province, goldfish can grow very large.
Alberta’s Fisheries Act specifies that actions must be taken to remove non-native fish species, including goldfish, from natural and artificial water bodies due to potential risks to native species and their habitat.
Goldfish owners should bury dead fish, rather than flush them down the toilet, where carcasses can end up in the river and introduce disease.
Under provincial law, those who release live fish into lakes or rivers can face fines up to $100,000.
pcowley@reddeeradvocate.com
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