When I make one lap around our pond I see minnows, bluegill, bass lurking just outside of range waiting to pounce, tadpoles when seasonally available, as well as tons of wildlife prints in the mud; raccoon, deer, turkey, etc..Near the feeder I always see a cloud of bluegill with occasional bass cruising through too. Here in South Mississippi, our bluegill have already spawned at least twice(April and May). You can see their beds and the rigorous activity of individual fish.
A healthy pond is going to be teeming with life inside and outside on the perimeter.
We do not fertilize, but we do feed three times a day. Our clarity is around 36 inches most of the time; heavy rains do muddy it a little bit, but it settles quickly.