My brother-in-law decided to spend the money on a new outboard motor for his boat so we are going to put in a couple garden beds instead

Here It gets only a little snow for a few days a year, Above ground ponds are also easy to insulate using 5cm thick styrofoam panels between the frame and the liner. The other consideration in this case is that in a few years he will sell this place and an above ground pond can be taken down in a day but filling in a big hole is a real pain in the rear.
The design called for 10cmx10cm posts, 5cmx20cm wall boards (set on edge), and mitered corner, 5cmx15cm capping boards held together with countersunk carraige bolts. It would have held approximately 10000 liters of water. tThe pump would have cycled the water once an hour through a filter made from (2) 120 liter pickle barrels and returned it through a spray bar.
Our initial plan was to stock 6 brown bullhead cats, 1 small mouth bass, 12 bluegill sunfish, 6 northern pike minnows, 1 of the small sturgeon (either a sterlet or a stellate)

, and a small bucketful each of gambusia and redsided chub, maybe 12-24 crayfish as well. The plants were to be pond lilies, japanese lotus and long leaf pond weed. The only fish we would have had to pay for was the sturgeon, the ones from around here get to damn big. I am bummed he changed his mind.