Since Thiaminase deactivates Thiamin/B1, it stands to reason that a diet containing a percentage of feeders that contain the enzyme should still be safe as long as the overall diet contains sufficient quantities of Thiamin to fulfill the animal's needs. It isn't necessary for each and every feeder to be Thiaminase-free, as long as those containing the enzyme make up only part of the overall diet.
Just another reason to ensure that if natural foods are used, as opposed to commercially prepared "complete" pellets, it's important to provide as wide a variety as possible to provide proper nutrition. I have used home-bred Rosy Reds and frozen bait store Smelt (another Thiaminase-containing fish) for decades as food for predatory fish, turtles and snakes without problems...but the animals received other fish, earthworms, insects, crustaceans, etc. as well. Being terrified to ever feed a "thiaminase fish" is a bit of an overreaction. They're not toxic or poisonous; they simply lack B1 and so don't provide full nutrition if fed as an exclusive diet.
Just another reason to ensure that if natural foods are used, as opposed to commercially prepared "complete" pellets, it's important to provide as wide a variety as possible to provide proper nutrition. I have used home-bred Rosy Reds and frozen bait store Smelt (another Thiaminase-containing fish) for decades as food for predatory fish, turtles and snakes without problems...but the animals received other fish, earthworms, insects, crustaceans, etc. as well. Being terrified to ever feed a "thiaminase fish" is a bit of an overreaction. They're not toxic or poisonous; they simply lack B1 and so don't provide full nutrition if fed as an exclusive diet.
