I have no clue of Raccoon eating habits, but they are mean little suckers! Before we moved to our house we live in now, I rented a Town house and it was by a Marsh area and at night we would see all sorts of raccoons running around the field by our building. We went to go to Wallmart late at night and their was a "sick " one by our door to get to the van, it made noises at us and acted as if it would come after us, they usually would scamper off if you made a noise. I had to call the police station and they came out to take a look at it, the officer said it looked to be rabid
with the way it acted. He had to shoot it. It did turn out to have rabies too!
I am sorry about your pond and fish
