.My husband and I are new pond owners and recently added three koi to our pond. After placing them in our pond, they are suddenly gone. We feed them everyday, but I really don't know if they are even in there. Are koi known to hide in rocks or plants? We can see to the bottom where all of the rocks are, but we never see movement! Also, now there are small black tadpole looking things. Any ideas? Clearly, we are new to this whole thing!