Not yet, but I have 3 small ponds. Unfortunately Mom and Dad put water lillies in one of them and they have really multiplied more than is good for fish or any kind of control......and I can't figure how to remove them. Also, I have to have a way of keeping the water level higher, so I might have to empty the ponds and put in a liner before allowing the water to fill again, because our parish has a levee system and controls the water table pretty closely (don't tell FEMA....they are under the impression we have no protection....whatever). But I think if I can stop the water from being sucked out into the ground and out into the gulf that I should be able to stock the ponds. That would be one of the cheapest farming projects I would have started, seeings as I already have the ponds.
I would like very much to have a pond. Someday....
Permaculture-type people use multiple layers of carpet and painters plastic to make cheap pond liners. It's very appealing and easy enough to clean up if you change your mind later.
I've used a slab of styrofoam and put coconut coir jiffy plugs in holes and floated it above my gold fish. it grew great plants and we had several big salads before the roots got really big and the gold fish started eating them. Koi are even worse on vegetation. I used to swing by a big local garden/nursery and get the green duck weed off the top of their water plant tanks for them as the koi just love that stuff. I had a smaller pond that I used to grow duck weed and watercress for the fish using their water.(my decorative ponds are one above the other with a nice little water fall between them) But I couldn't grow as much as they needed for food so I also fed pellets. but all the plants I had in the pond and water fall thrived with the fish poo running thru.
I want to get a couple of the big blue barrels and start a small aquaponic garden They grow greens and lettuce all summer without them getting too bitter.