OK, question. My sister, the one that lived in AZ, moved to WI, did a hurry-up-and build-a-pond last fall RIGHT after they bought house and moved in. Now, this spring, the 6 large koi she had shipped form AZ (to the tune of well over $1,000 just to move them ...) plus the 12 or so smaller koi she bought "to cycle the pond" last fall, are disappearing. I told her it's a heron, since she saw one in a neighbor's yard. She thinks it's the raccoons. Then she said maybe it's a peregrin falcon, or a hawk. IMO, the only one of these that's likely is the heron. Let me describe her yard (and subdivision that she lives in) . ALL the yards have huge very mature trees, probably 50 years old or so. Her back yard where the koi pond is has almost 100% shade coverage from huge pines, spruce, and hardwoods. The koi pond is just off her back patio, which is attached to the house. So, I don't see any hawk or falcon "diving" for the fish, as she seems to think they are. And, I thought raccoons only fish in shallow water where they can corner their prey. She is down to 1 large fish and 2 small ones. I told her the predator will not stop until they are ALL gone. She says no more koi "but we may get some shubunkins, because they are pretty, too!" I asked why not put up a fence, she said, "We want to see our pond, no look through a fence." So I told her no more fish then, if she can't keep them safe.
Your thoughts?