Hi Lee,
The thread Suzoo was talking about is here (
Thiaminase and a Hello to you all.). Look down near the bottom. I don't know where you are in the U.S., but if you're on a coast, salmon are a good source. Otherwise, you might consider trout, bass, bluegill, crappie, or perch. You can buy a whole fish or a fillet in the supermarket and cut off small chunks after it's frozen. Then just thaw and serve. Leave the bones within, unless they have particularily sharp edges. It's also a good idea to dip them into vitamin powder (Calcium & Vitamin D) once in a while.