Both fish, Halibut (Hippoglossus hippoglossus) and Salmon (Salmo salar) Salmon (Coho) (Oncorhynchus kisutch) are both on the safe fish list as it pertains to Thiaminase. You bring up a good point about other contaminates. I would check with local gov. agencies to get an answer to your question. I'm sure they test the fish on a regular basis.