There was already a thread about this in the Cyprinid section. It's actually a pretty big problem as there are established populations of goldfish in most states. Really makes me wonder why their ownership hasn't been banned yet like some other invasive plants and animals. Like carp, they can easily muck up a waterway.
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USGS map of goldfish populations in the US
But I think that's Cyprinus carpio not goldfish. I have a friend from the Czech Republic, and they eat carp as their holiday feast.My family eats carp and it's consider a very good fish to eat in Poland..