The minnows and one koi in my dad ponds looked funny a few weeks ago. I notices what appeared to be feathers growing out of their skin. I removed one of the minnows and did some research and found that our pond has been infested with Anchor Worms. These are a parasitic animal that attach to fish. Its very hard to get rid of them once they are in a pond. We quaratined the fish and are letting the pond dry out which will kill any eggs in the water. The koi will have to be seperated from the minnows to make sure they dont cross over. Only one koi had an anchor worm on it and it was removed so they are clean. The minnows are slowly dying off. I took some up close pictures of the worms.
http://www.gather.com/viewSlideshow.action?albumId=37483
http://www.gather.com/viewSlideshow.action?albumId=37483