All the packers except the commercial ones with a glass lid and a vacuum chamber suck liquid through the pump. Some of the Tillia machines even have a foam filter and a little sump on the bottom that you can empty out. It's not really a big deal, you can give your packer a little warm water douche (drink, actually) after you use it, then suck a little silicone lubricant into it to lube the cylinder. This keeps the machine from having bad breath (stale fish smell the next time you use it)

I pat all my fish fillets down with paper towels before I put them in the vacuum bags, it works well.

By the way, I've got two Tillia Foodsaver machines and one Magic Vac or something liek that, they are all basically the same machine, all of them are old and work well. One I bought at PMG rebuilt for $85, the other two I got at yard sales for $5 each.

-N.