Aundrea, from what I understand they're not as bad as goldfish, but do contain thiaminase which should be avoided. Like I said, I do use them sparingly and wouldn't hesitate to use them for a non-feeder, but probably not worth setting up a tank for. Now Wayne's awesome minnows from his creek or guppies as Gertie said would be awesome and I'd love to have a feeder tank full for my guys!