I've found a year max on a well sealed bag. After 6 months I smoke it. Taking off the skin will help. I wipe down my fish with paper towels now and have stopped rinsing off my fillets before I seal. Canning is also a good option. It's better than store bought tuna any day! One more...I don't use a frostless freezer for ANY of my fish. That slight thaw and re-freeze is brutal on quality.

Brewer is right on. A high quality sealer is more important than my tackle.