If you ever fileted fish and left them in a ziplock for a few days you will see how much moisture is lost from them. I fillet my fish and do not rinse until I defrost (unless guts explode). I let them sit in a ziplock for 3-4 days in the fridge, pat dry, then wrap in plastic wrap, freezer paper and the vacuum seal. As mentioned, a slow fridge defrost that takes 2 days is best. If you are rinsing before freezing, those chemicals are breaking down the protein much faster this making them even more rubbery. Just rinse then soak in ice water for an hour before you cook them. Tautog, cod, crappie and cusk all seam to need this extra help IF you really don't enjoy it otherwise.