Two of my Koi died last weekend and floated to the top. I am in
Chicago and have kept the ice from freezing over with airstones and a
heat source. I am wondering if they just got sick (they were covered
in slime) or if something in the pond caused it. The water is quite
brown from all the fall leaves. I tried to keep out as many as I
could, but a large number (realtive to pond size) got in. Next fall I
will cover the pond with netting. Could this have affected the fish or
does the water just look ugly to us?