The pond I bought was established and fish-less despite having lots of frogs. I couldn't believe there were no fish in it so I got a bunch of lively worms and tossed them in at various points and watched what happened. Every single worm wriggled its way to the bottom unmolested. Also, despite calm summer evenings with lots of bugs flying around, I never saw a rise in the pond.

So what I did was stock a bunch of fathead minnows in the summer, then released bluegills in the fall. The next summer I put in tiny bass. The following summer I had 12 inch bass. All I did was take the advice shared on this site and I have a really nice fishery (but with a lot less frogs!).