Food for pond goldfish?

I live in a little town and the one place where I could get goldfish pellets for my ponds has stopped selling it.

For the last few days I've been smashing dog food kibble and throwing that in my ponds and they are eating it, but
I don't know if there would be any bad effects of doing that...

Anyways just looking for ideas on goldfish feed. (homemade, other sources,etc.)

Thanks

Talking to some pond owners I have heard repeatedly that the pond itself will provide in the form of algae and invertebrates.

I'm just wondering if the ponds are too small for the number and size of goldfish in them. These are lined "ornamental" ponds with a good layer of
leaf mold and stuff on the bottoms, but I don't know if they would naturally make enough food for the fish on their own.
There are lots of plants in though.


Of course it is getting colder now and fish eat much less and are less active as the water temp drops, so I'm not afraid of them starving, just maintaining them.