If you want to use it as a forage pond, you need to remove all the predators. That means killing the pond off and starting off with just the forage fish. Rotenone applied by a licensed applicator, or drain down the water, apply hydrated lime until the pH reaches 10+ wait a few weeks and refill with water. Test water to ensure pH is correct, then add the forage fish...
Unfortunately, esshup's correct. A few missed predators can decimate an entire class of forage. Foot prints, puddles just above the pond, or any water adjacent to the forage pond needs to be treated.
