It sure is fun catching fish on a little noodle rod with light line. Even small fish put up a good battle. On my ultra lite set up I use 6# trilene XT. I like the added abrasion resistance and tensile strength when you need to move a fish from around cover. Since the line is a little thicker than 4# I use the green color which is invisible in the water. Make sure to check for nicks in the line and retie often. Good luck!