I have two rats, Basil and Winston. Both of them have an amazingly agressive food response and will attack anything that even brushes up against the wire on the cage because they think they can eat it, I have been bitten a couple of times just from accidental contact with the cage. I don't usually feed them through the wire because I know that they will associate things near the bars with food but occasionally food will get passed to them through the wire. Please help! How can I stop this behavior?