Inheriting unstocked massive pond. What to stock?

Buying a house. Has natural stream-fed, hard-pan dug-out pond of approx 30,000 gallons. Freezes a little in winter, most likely. Starts out about 9' deep and shallows out to around 2 feet. Has dark enclave in the deep. Monster can hide.

Thinking oddball coldwater here. Something that can handle a winter and freeze-over. There are thousands of coldwater fish I've never heard of that I could put in here. I'm thinking sturgeon, wels, LMB, blue catfish, but what would YOU, my dear enthusiast, put into the cold void?

Part of me wants to throw ungodly amounts of different sunfish in there, but I know I really want that giant wet pet.

Sorry. Meant to post this in POND.

Kind of had my heart set on a wels, but I guess they're hard to get. Any similar giant catfish? Blue cats seem pretty neat, but do they hide to the extreme, or will they come up for food like a channel?

Agree on the pathogens. Stream that leaves the pond is too small for most big fish to flop through. But, yes, I did mention the stream-fed aspect for that reason. But the only local catfish are all bullheads. Tiny. Now I've been reading up on blue catfish and I really think it might be a good fit. Can they take the cooler temps of the Pacific Northwest?