Hi from UK

[OllieOtter1994]

Your koi could be hiding in there. I’m wondering if your various silver fish/ roaches are eating the other fish, or just out competing them for food. Try getting some pond fish food and tossing some out daily. Same spot, same time, every day, they’ll Lear to associate that with free food, and eventually you’ll see all of you surviving fish.

Thanks for that Jamie.

The roach / silverfish added are not predatory and are docile fish. There are thousands of roach fry in the pond which I can see when going round the outskirts of the pond.

We have some floating pellets which we regularly put in one side of the pond, this is teeming with the roach now, but last year the grass carp would happily feed in the vicinity of them without any issue.

This is my worry! All of the fish (except from the koi which we never saw following their introduction in October 2018) were pretty visible nearly all of last summer, but no sight at all this year. Now all the rest of the fish have came out again - the roach are always about, and the remaining goldfish are easy to spot and feeding on the surface. I sadly don't think there are any koi or grass carp left!!

 

[JamieB]

You might have had otter and herons get them, which would be sad.