Old John,

Welcome to the forum. Its a great source for info and fun.

The trees in the dam can be a problem. The roots and the wind swaying the tree and loosening your soil can combine to be a big problem. Remove all the small ones. If there are very large trees, get a professional to make an assessment.

Also, a note...20 grass carp in one acre is a lot. I know some agencies recommend that kind of stocking rate, but its too many for the long haul. They will soon run out of stuff to eat and may cause you water quality problems.