Great Lakes Fishing
Freezing or vacuum sealing fish
The enemy of frozen food is oxygen, (air). If you are having leaks with your vac sealer you need to look for the culprit that is causing the leak.
One problem for leaks is a punctured bag. Bones or Sharp edges can make a tiny hole in your sealed bag and air will get in. Be aware and examine what you are vac sealing.
Second big issue is fluid coming from the fish or fillet and getting into your sealed edge as you are sealing. This will always cause a leak.
What can you do to remedy this issue. Take your fresh fillets and pat them dry with paper towels, then place fillets on big cookie sheet and flash freeze for 10 minutes in deep freezer. Place flash frozen fillet carefully into bag with one end presealed. Try not to smear fillet fluids onto the opening were you will need to seal again. I then place a folded paper towel which crosses the width of the bag up against the fillet. Once again make sure opening is clean and dry. Only then, seal the last open end. Done this way the fillet will last a long time. If you can do extended vacuum and seal on your machine, do it. You can't get too much air out.
The mention of cling wrap around the fillet first is a good idea and I will give that a try to see if that makes process easier.
Good luck, Shellfish