John Monroe, The picture of black clouds in the shallows may be American Toads rather than bullfrogs. If they are still there, pick one up and look closely. See if you can see a 'spiral' imprint on their back. We also have clouds of black 'toadlets' in our shallows just like you. The American toad spends its life out of water, but comes to water to lay eggs. If you check daily, when the toadlets are big enough they will all come out of the water at once and head for the woods. You will see the grass just alive with wriggling toads trying to made it to freedom.
The bullfrog tadpoles take 3 years to become adults and you will likely not see clouds of them. They tend to be more green (not black), their tails are not tiny corkscrews but more broad blade like tails. They move much more quickly than toadlets, to the point of hardly being able to see them dart.
Cicero, you can source bullfrog young pretty easily on ebay, they sell by the dozen or larger quantity, you can pick their size. But once you stock them it isn't clear why sometimes they stay and reproduce and other times they grow up and leave.
