Nightcrawlers are one of the most popular types of live bait to use for largemouth bass.  Most nightcrawlers that are sold in bait shops will be about 5 to 7 inches long.  Anglers will typically use hooks in the #2 and #4 sizes when they are using nightcrawlers.  One of the nice things about using nightcrawlers as bait is that you can catch bass from 7 inches to 7 pounds with the same size bait.  A live nightcrawler gives anglers the opportunity to have a lot more action because you may also catch bluegill, smallmouth bass, walleye, catfish, perch, rock bass and other sunfish.