Preheat oven to 350 degrees F (175 degrees C). Lightly grease a baking sheet with vegetable oil.
Drain tuna and reserve oil; add enough vegetable oil to make 1/4 cup total. Combine tuna, reserved oil, bread crumbs, eggs, and brewer’s yeast in a bowl. Drop 1/4 teaspoonfuls of tuna mixture 1 inch apart onto the prepared baking sheet.
Bake in the preheated oven until set, about 10 minutes. Cool biscuits and store covered in the refrigerator.