I had some of my best crappie fishing out of a pond where many cows had died. You could see the maggots falling off into the water.
I'll second this for the crappie fishing, my favorite spot is on my old college campus, and there was a dead deer in the pond. Man it stunk after a while.....but the crappie bite was on. Whatever you threw in you got a big fat slab.
-Skinny