Question about a missing koi

[Michael from Daytona]

Gemma, raccoons are incredibly agile and clever. Judging from your photo, your environs look kind of rural or at least suburban, but regardless, you will find raccoons wherever you find humans. These guys have the capability of pulling up wire mesh and getting under it. I would suggest that you rake any bare ground adjacent to your pond area such that any raccoon or other predator would leave prints. Raccoon prints look like this (a really big one visited me while I was about to clean sludge out of the bottom of my pond and left these friendly marks):

 

[Souper09]

I had a blue heron coming over for fish dinner, but I installed this item called a scarecrow that shot water at the pond and the heron couldn’t take the pressure and moved on. Never had a raccoon go after the kids in the pond.

 

[JamieB]

I’ve had floaters, no harm to the others. A single fish in that large an environment, even if you don’t find it, shouldn’t harm the others unless it died of a parasite, fungus, or bacteria. Then you have a risk of that infection possibly spreading. But I’d guess you keep your fish healthy, so should be no problem.

 

[Gemma]

Gemma, raccoons are incredibly agile and clever. Judging from your photo, your environs look kind of rural or at least suburban, but regardless, you will find raccoons wherever you find humans. These guys have the capability of pulling up wire mesh and getting under it. I would suggest that you rake any bare ground adjacent to your pond area such that any raccoon or other predator would leave prints. Raccoon prints look like this (a really big one visited me while I was about to clean sludge out of the bottom of my pond and left these friendly marks):

I do believe that raccoon can lift the mesh and get under it but, I have no shelves in my pond (4 1/2' deep) so it would have to swim after the fish and at this point why go after just the 2 smallest ones? I'm thinking a raccoon would have had better luck catching the larger and slower fish, and would not have been able to set the mesh panes back the way they were

 

[Michael from Daytona]

Good answer, especially about "setting the mesh panes back the way they were." So it ain't a raccoon. I lost the smallest of my dozen goldfish, a 3" fancy-tail I named "Tiny" (because all the other goldfish had tripled their sizes), to a predator but I couldn't tell what kind of predator. I don't have any anti-predator devices such as mesh or decoys, and until I saw those 'coon prints I was thinking that I was pretty well off security-wise. I've allowed floating water lettuce to cover 50% of my ponds in order to give the fish something to hide under. They usually come out when I check on them in the morning, expecting to be fed, but every now and then I have found them to be very wary and anxious. Like you noted, I would expect predators to attack the largest, slowest fish (2 koi about 12" long) but this has not been a problem.

 

[herzausstahl]

If the half dozen dead frogs at the bottom of mine didn't harm my fish a few years back I'd venture to say your ok.

 

[herzausstahl]

I shud add it was after a harsh winter that my fish survived