I understood the added chemical was causing the problem but it doesn't seem worth it to me to risk feeding any pre-packaged fish if there's a risk of the fish being treated with harmful substances. From my understanding my snake can get full nutrition from eating only mice and worms. I can see the need to feed fish if snakes refuse to eat mice. Are silversides safe from these chemicals? Can I buy silversides at petsmart? My snake seemed to like the fish and accepted it immediately, so I would be willing to feed silversides if I knew they were safe. If not I will probably just be avoiding fish in the future