thiamanase shmiamanase. Mayonnaise for that matter. Raised garters for years before anyone heard of such a thing. With a varied diet, I saw no sign of disease. In fact, the pair lived exceptionally long lives.

Still, Lauwersp, you should try to get them feeding on frozen/thawed silversides. Most snakes that will eat live fish can be easily converted over to thawed fish. Might also want to try slipping in some pinkies in their fish.

I know some garters aren't very enthusiastic about feeding on dead food. Get a ceramic or non-porous dish and put some fish in it and give them a few hours and some privacy in their enclosure if you're using a safe substrate. Sometimes, the fish disappear when you're not looking. A few hours after "sunup" when the snakes do their basking, get up to temperature, and then.. that's the perfect time to feed or try new foods. Holding back food for a week can also help.

As far as the paper goes, newspaper is relatively safe, including the ink as far as I know. Don't use the glossy ad type paper. You can shred regular newspaper by hand very easily. If swallowed, it doesn't present a problem. It's easily digested.