I have a large salmon filet that was tossed into the freezer in its original wrapping (styro tray and plastic wrap) a few months ago rather than cut up and frozen individually in ziplock bags as I usually do...have never had occasion to cook such a big piece of fish and now it's not looking so good. I hate to waste it but is it ruined? I've thawed it now and much of the surface is lighter in colour and kind of off-looking, and it smells a bit fishier than I would normally like fish to smell...but I find frozen fish does usually smell fishier than fresh...so should I bother cooking it? Cut off the sketchy-looking parts? What is freezer burn, anyway?