That is a fat snake, agree with @mrsclem, a northern water snake. They are quite adept a catching fish too, hopefully it is getting its fill on all your frogs.
Have a garter snake hanging around the pond eating the juvenile frogs, even with me out there working on the pond addition I have seen it a few times hanging out with a bulge in the middle of its body.
Have a garter snake hanging around the pond eating the juvenile frogs, even with me out there working on the pond addition I have seen it a few times hanging out with a bulge in the middle of its body.