> invasive fish species all over the world
  > introduced by humans for "sport"

Not just for "sport," IIRC there are some invasive species in the Mississippi River that got there when one of the floods engulfed some fish farms/hatcheries that had some exotic fish there to help maintain pests/algae/etc.

Also, Florida has a lot of iguanas (which are non-native), especially in the Everglades, you just don't hear much about it because the pythons are a larger issue.