Goldfish are not tropical fish. They are every bit as hardy as true carp. They belong to a group of closely related fish that actually go so dormant in winter that they can survive without any oxygen. They have naturalized in some places and have reverted to wild form in some places and then they are not gold either. Then they resemble small carp but lack the barbels. BTW you may here some immigrant mention that in "my country" we eat the little carps. They are referring to the goldfish family and they are supposedly better eating than the much bigger true carps. They never get over a couple or three pounds usually but they fight as hard as their bigger cousins pound for pound. There are at least a couple of metro ponds with the reverted goldfish or perhaps the Crucian carp, which is nearly identical, where one will catch them once in a while. Lots of fun on light tackle.

The question of goldfish as bait is moot up here in Minnesota. Here it is illlegal.