We've had one for a few months now, I use it for anything I want to keep air off of. It works great for block cheeses, they don't lose their moisture, and meats.

I started using it for frozen fillets without having to screw with water. Its cheap, at walmart, and the bags are cheap. Plus you can suck until you're getting fish juice, and just wash the tip/reservoir out. I would think this is a better way to keep the texture of the fish without oxidizing than freezing it in a block of water.

Heres the link if you're curious: Reynolds Handi-Vac