Don, Don't know how many acres you talking about total, but unless it is real steep I would look at tractor and bush hog, I had one of those 11 HP Swisher trimmers once and they do ok, but if it is too steep for tractor it's probably same for four wheeler. I run up and down grade when it's steep, or from top of bank down to water but have front bucket on for weight.
As for the fish, we always had perch and catfish in ponds, and they multiply like rabbits.