I think that if you've gutloaded your fish, you don't really need to kill them. They eat only live fish in the wild and don't need reptomin, which is basically just fishmeal anyway. feed my matamata all live fish (4-6 dozen at a time, now :P). However, there shouldn't be a health risk to feeding freshly killed fish. I've heard you should deworm them every 6 months, which seems like a good idea to me.