I've posted the list from literature search that I made of thiaminase-containing and thiaminase-free fish several times on the MFK. Since then Ive learned that the Tennessee Public Aquarium head vet at Chattanooga professes that all frozen fish contain thiaminase, some more some less. I've not figured this one out yet but this info carries a lot of weight due to this vet's position. Ive solicited input on this from other vets, from University of Florida, and private, but vets seem reluctant to discuss the opinions of their peers with others, like us the hobbyists.