The freshwater habit is interesting, particularly because:
a whole lot like a bull shark
Bull sharks are infamous for occasionally swimming up the Mississippi river (as far as Illinois!) and surprising people who were definitely not expecting to find an aggressive shark in their swimming hole.
Ouch, I can see what they don't like that surprise! The bull sharks can actually be pretty scary, because they can do this in most big rivers in almost all parts of the world. Nowhere is safe from them!