Pond Boss Forums MANAGING AN EXISTING POND Fertilization Vanishing fish

This is a koi pond question I know it's not the norm for this forum. My parents have a koi pond in their backyard it has four large koi 6-9# and probably twenty six to eight inch assorted goldfish. The yard is fenced but backs up to some open land. They have seen a gbh come around but run it off when seen. The pond is about three feet deep over the last few days all of the goldfish have disappeared no sign of fish remains or scales. I don't think the gbh could have caught all of them without being seen. The koi are fine it's not in a path that an otter would follow and by my experience they would have killed the larger fish. Too deep for raccoons to do any damage. Does anyone have an idea what else might be the cause

My neighbors (in the city) have two koi ponds. The have a 3' deep one beside their back deck. They also have a 7' deep pond to overwinter the koi.

The 3' deep pond was cleared out twice by raccoons (they believe). I know they caught the raccoons in the act the second time.

Any cameras available?

No cameras available. I discounted raccoons because there was no evidence left

On very foggy memory - I think the first clean out was in the spring, and the culprits left no evidence.

The second clean out was in the fall, and the raccoons were eating the fish beside the pond.

Perhaps raccoons with young in the den during the spring would take the fish back?

(Wild speculation on my part!)

Maybe need to buy some cheap goldfish and throw them in the pond and set up the game camera to determine the actual villains?

I don't think any amount of "detective" work can resolve this issue based on the available evidence - or lack thereof.

Any fish hawks or eagles?

We have GBH taking fish out of stock tanks in western ks often enough they have pretty much quit doing it (stocking goldfish/koi)..
I would think water would have to be 6-8" or less to have Coons be very successful..

No fish hawks or eagles. Virtually no shallow water. Yes I don't think we can come up with a definitive answer was just hoping someone might have a suggestion that I didn't think about.

As inexpensive as game cams are now that might be a solution to who or what is getting them

I know we built a bait pond to raise goldfish for river bait, when it had a couple feet of water in it we put a hundred GF in it, water was around 2' dp at the center. GBH cleaned it out in a matter of days, didnt take them long at all. all of the GBH didnt survive but enough did.

And they were a fight from day one to the last day we tried raising them, something about the brightness of them they love them, eat em like candy.

GBH also feed at night. They can get fish from the pool close to the house without being seen at night, and take a look at the moon cycle now......... They have young ones in the nest, so they are much more active now.

GBH night feeding is what I think is probably the culprit