Pond is doing great. Crystal clear, snails, water boatman, plants. Koi all healthy. Yesterday, I go to step over the stream and see a white rock covered with what seemed to be short black algae waving in the current. To I grabbed the rock, dropped it in an aquarium for a closer look and immediately hundreds of the small black animal began scrambling up the side of tank alternately attaching one end with the other. Im pretty sure these 1/8-inch things are leeches. All of the Gambusia that I have removed from the pond to the aquarium appeared mildly interested in eating most but not all. I have no more Gambusia in my pond because I did not want them to be predators of my 50 or so Flag Fish fry. Will the flag fish eat the leeches?There's hundreds, perhaps thousands of leeches in the stream. HEEEEEEEEEEEEEEEEELP! What do I do?