Yes I would think an eighteen inch corn can eat a fuzzy mouse. Try one small fuzzy first.1 1/2 times the thickness of his body.
I bought a baby 12 inch corn that would not eat a pinky nomatter what I did.Live or frozen , Brained or cut up . Put them in a bag , drove them in a car all the things they say to try ;did not work. I tried for a couple weeks , then I went to the pet store to get make a lizzard stuff , and the guy said "here dont bother with that, feed him this" , and he gave me a live fuzzy . I looked and said " no way he could eat that he is just a little guy". Well the snake seen that fuzzy take 2 steps and wham he was all over it . Squeezed it and ate it no problem. So all he had was fuzzies .