Not only that First of for thouse that dont know thiamine its a enzime that bonds with vitamins of the complex B and degrades them, unabeling a animal that eats something that has it to absorve the B vitamins wich he needs. This causes the animal to became deficient in B vitamins , particulary biotine, wich is potencialy fatal. There´s more. First of this enzime greatly increases in frozen foods particulary fish and more if its oily. But also can be destroed or inacivated if we expose the desfrosted fish or mouse, rat ,etc to heat. That why its good to thaw feeders wich we are going to feed herps with, in water that is at least 80 F. We dont sufer the efects of this enzime because we cook food The other thing is that some foods are naturaly high on this enzime. One great example is gold fish, wich also gives credit to my theory that they are a very poor choise as feeders. Mosquitofish and minows are much healtier