They are an invasive species everywhere except the amazon. Where they actually have natural predators. You can't legally own one unless you have a license here in Canada.
They are the 1 fish you are told to kill immediately and report it if you catch one.
I kind of wanted one for my pond haha instead of koi
They look like goldfish when young, which is how I think they were introduced here. Grew up to be ugly and they tossed it. Only thing is, they can live (and thrive) in pretty much every water condition other than bleach. Others say they hitched a ride on a ship, which is also believable.