Here's a couple of links. I have used Peterson's guides before, but not this one in particular. Might be too much info. for some. Not sure on the Audubon guide.
Peterson Field Guide to Freshwater Fishes, Second Edition (Peterson Field Guides): Lawrence M. Page, Brooks M. Burr, Eugene C. Beckham, Justin Sipiorski, Joseph Tomelleri, John P. Sherrod: 9780547242064: Amazon.com: Books
National Audubon Society Field Guide to North American Fishes: NATIONAL AUDUBON SOCIETY: 9780375412240: Amazon.com: Books