One lone goldfish left in my little pool. He was about 1 1/2 in long when I put him in four or five years ago. Now he's about seven inches long and all his mates have disappeared. The water is looking a bit stagnant. Usually fresh water is flowing in which keeps it cleaner.
Excellent Beth, you must have had a visit from the herons, they can see from high up in the sky, that there is water below, and probably has been inquisitive and taken your fish. Cover your pond is my answer.
