All natural water bodies are considered the jurisdiction of the States wildlife and fish management agency. The land and "pond" may be privately owned, but the actual water and wildlife therein are the ownership of the State - and yes, I'm being serious here.
Now, if the pond is man-made and privately stocked, then this is seperate matter, but again it is regulated by the State (i.e size limitations is one example) and has restrictions as well as permits enforcing the use(s) of the water and the wildlife (i.e. cant charge for fishing, can't remove live fish from property etc.). Some states require nets and fencing to keep "true" wildlife from carrying away any fish in the ponds i.e. Herons, racoons, etc.
Just FYI
This is a very serious topic, that most people blow off
It's almost like the cliche - "It won't happen to me!"
It's kind of the same mentality; "It's only one fish", or "It was only in the tank for 10 minutes..."