I've never used a vacuum bagger, but I imagine it works well. I've always rinsed them in cold water and froze them as soon as possible. Whether freezing them in baggies or milk jugs, as long as they are immersed in water, the outcome is the same. The real culprit that allows degredation during freezing is air. Regardless of how you freeze the flesh, if you allow air to touch it, it dries out (aka "freezer burn"). As far as post-catch treatment, the absolute best is to keep them alive as they were in the wild - fresh water - until they meet the fillet knife. Keep them alive in fresh water at the temp that they have been acclimated to. Crappie thrive in frigid water to hot - 33F to 90+F. But if they have to be stored or transported, ice them while they're still alive. Allow the melt water to drain away from the fish - never keep them in water. If they die, they start to decay. Icing only slows the process. I've got fillets in the freezer that I dated in 2010. They're still grade A
If you ever get a chance, watch a TV program on how the commercial fishermen freeze fish. They flash freeze it. For instance, they will take a whole salmon and put it in the flash freezer which is A LOT colder than a normal freezer. Then they will pull the fish out after a short period of time, dip it in water to form a nice protective layer of ice, then back into the deep freeze.
So what's the point of this method you ask? Well, the faster you freeze water, the smaller the ice crystals are. Smaller ice crystals don't puncture the cell walls of the meat, so the meat stays firm. Ice cream is similar, the colder the ice cream maker, the smaller the ice crystals and the smoother the ice cream.