Vacuum is the only way to go. Now that being said, I read a post on the SC board the other day where a guy placed his fillets in a ziplcok bag and submerged the whole bag under water getting all the air out. Then he'd push out 1/2 of the water (or more ) out of the bag and zip it while still under the water. IMO, that would be even better than filling the bag full to help conserve freezer space plus they would thaw alot quicker when youre gonna cook 'em.