We have started work on our farm property and one of the first things we are doing is to excavate for a farm pond; which means we have excess soil. Send me a PM if you are trying to source dirt on the cheap. Shawn
The pond is just over an acre so there is a bit of soil that will be available much cheaper than what we sourced when we backfilled for our house. Here's a couple pics. Shawn
Good luck! A buddy of mine took on a similar task a few years ago to build a self sustaining pond for swimming and fishing. His was similar in size and 15 ft deep. His ground didn't have enough clay so he had to use a liner to prevent water loss into the ground. Evaporation is replenished by rain or a water hose since there is no natural flow. Initially he had aerators, but no longer uses them. He spend a lot of time figuring out what he needed from plants to fish to create a self-sustaining environment. It probably took about 3 years before he didn't need to stock minnows or feed fish food to maintain the larger fish. Now the challenge is to take so many fish out of the pond so they don't eat all the smaller fish and die off. A never ending labor of love. lol
I would just spread the soil out and plant vegetable's around 2/ 3rds of your Fish Pond. Add Fencing for sure!