Do not be concerned about turtles, I have literally hundreds in a smaller pond and they do not effect the fish at all. If anything they might help by cleaning up dead stuff. They are also much slower than fish and won't get that many pellets once there are a bunch of fish to eat them. Wading birds like herons don't take many fish and are only annoying when they kill a bigger fish, but in your case they really aren't hurting anything although I would scare them away for about an hour after you stock anything. The only animals that will damage the pond is cormorants, anhingas, and otters (legally I can't tell you to kill them).
Thanks. Sounds good on the turtles.
In the past, we have had otters on multiple occasions. God knows how many fish they took because it was before anyone was paying close attention and spending a lot of time there. So, not sure how long they were in there. The last couple of instances, a couple of guys who help us look out for the place just happened to notice them. Thankfully they are gone now, but we are keeping a close eye, especially right now because it has been so dry and the pond is low.
