Read the last post I made below. I've kept nerodia before, all wc for the very reason you stated, nobody breeds them. All that I've had acclimated quickly, though I must say they were very young.
Adults tend to be a bit nasty.
I've always started them on feeder guppies, then moved to gold fish,increasing size as the snake grew. I've personally not introduced rodents,fish are so easy, but with their feeding habits I can't see that you would prolems with any prey item as long as it's sized right. Personally, I believe a varied diet would be the best. Read the last post I made below. I've kept nerodia before, all wc for the very reason you stated, nobody breeds them.