I have had a pond for 15 years with no problems. I have used this forum for many years and have read and learned new things. I alway cover my pond in fall so leaves do not get into it. Then I uncover it early December before our great WI freeze. This year the fish were all fine when I uncovered it. We have had tons of snow and extreme weather here so to get to the pond has not been easy. Got there the other day and found to my surprise all 20 fish I have had for 15 years are gone. No where to be found. I have always kept my fish out in the winter with a heater and our pump running. Heck the pond barely unfroze except for the open spots. Another strange thing is that there was a lot of algae. I never saw this in winter hear. This is just so heartbreaking. Now I look at the pond and am so very sad. I told my husband I think we will just fill it now. No more fun with the grandchildren. They loved to feed the fish. I can never afford to replace all those beautiful fish that were so dear to my heart. I can't imagine what have gotten to them in winter. This is so strange. My pond is very close to my house I can see it well from my kitchen window and is is alway lit up. Sad thing to happen for a new year. Thanks for all the information I got through the years, I wish all you ponders a wonder spring and summer with your ponds!