Torchy,
I was wondering how my pond suddenly become populated with black crappie. About a year after the problem arrived; my wife's uncle asked me if the crappie he put in my pond survived. For revenge, I often put turtles and large snakes in his pond, he is deathly afraid of snakes. My bet is on the neighbors or friends.
Also, I have heard of tornados draining ponds and I assume thusly spreading fish and fish eggs. My Mother-in-Law said their 2 acre pond was completely drained by a tornado that also took their wheat bin and the roofs from their barn and house.
A lot of possibilies, good luck with the detective work.
