I personally would never try that.
I used to have piranhas and all 3 of them got very ill and died from store bought feeder gold fish.
I know that turtles eat fish, but I wonder if they're bodies are more equiped to handling various fish diseases, or if that's just part of the risk. I don't know much about them as pets. I would just think if a snake didn't eat it in the wild it might not be a good thing to try.