I was going to guess crucian carp when I first saw it but I realized it looks a little different then goldfish do and we don't have any here in the states. Then again you never know, it could've been somebody's pet. I've heard of pet owners releasing Pacu (a cousin of the piranha) in canals and ponds in Florida.Carassius Carassius
All over the Europe.
The crucian carp is a medium-sized member of the common carp family Cyprinidae. It occurs widely in northern European regions. Wikipedia
https://upload.wikimedia.org/wikipe...sCarassius8.JPG/220px-CarassiusCarassius8.JPG
I've heard of pet owners releasing Pacu (a cousin of the piranha) in canals and ponds in Florida.
big bass bait