salvage a salmon

I assume it was cheap because today is its use-by date? I would make a fish pie. Cook it in water until tender and falling apart, then drain it and stir in some of the cream (I'd do half milk and half cream or it might be too rich) and maybe some frozen peas and a bit of dried or fresh chopped parsley, and top with mashed potato. You could stick some grated cheese either in with the fish, mixed into the potato, or as a topping.

That should be okay in the fridge until tomorrow, or if you want to keep it longer then freeze it, and re-heat thoroughly before serving.