According to CBC News:
In one case, the municipality of Wood Buffalo pulled 40 of the domestic fish species from a stormwater pond.
"That's really scary because it means they're reproducing in the wild, they are getting quite large and they are surviving the winters that far north," said Wilson.
Forty! That does seem bad, doesn't it? And I'd like to remind you that these goldfish are surviving (and growing) in Canada, where it's cold.
"Their size is limited in the tank, but when you release it into the wild, that doesn't exist anymore," Wilson told The Washington Post.
Like other species of carp, the domestic goldfish Carassius auratus will basically keep growing as long as water temperatures and food resources support it. There are obviously limits - you're not going to accidentally create fishzilla if you overfeed your goldfish - but given a big body of water with tons of food and warm summers, a fish is bound to get supersized.
Then you end up with a bunch of goldfish bruisers competing with local fish for resources, and you better believe the fish you flushed will give native species a run for their money. Plus, some scientists say, goldfish feces might help support certain types of algae, leading to algal blooms that further disrupt the eco-system.
The CBC reports that a campaign designed to curb this trend, called Don't Let It Loose, will "focus on educating Albertans about the dangers of releasing domestic fish into nature."
If people are dumping their aquariums, Wilson explained, they're also dumping the water it holds, which can carry disease and parasites. What's more, the goldfish can survive in poor water conditions, she said, and "could be competing with our native species for both food and habitat."
