[Note, the identification below is incorrect. As others have pointed out, this picture is of a rock bass, Ambloplites rupestris.] That's a warmouth, Lepomis gulosus [No, it is not]. Keys are the bright red eye and the black lines radiating toward the operculum (gill plate) from the eye. I used to catch them on poppers on coastal NC rivers when targeting bluegills.
Steve [You know that you should be more careful when identifying Centrarchids. They aren't as easy as marine sculpins...]
Nice correction Scott (I hope that they don't take away my degree...)!! Yes, it is a rock bass. One key distinction between the genus Ambloplites and the genus Lepomis is the number of anal fin spines. Ambloplites typically have 6 (range 5 - 7) and Lepomis have only 3. The nice picture that chattmr uploaded would appear to have more than 3 anal fin spines; this tends to produce a pretty compact, rounded anal fin. Rock bass, Ambloplites rupestris, has a two-height anal fin, short spines in front, longer rays in back. Also, the rows of black spots along the body, especially prominent below the lateral line area, are pretty diagnostic. The dark oblique stripe from the eye threw me off last night. Here is a nice key to Lepomis species that has top / bottom pictures of warmouth and rockbass at the bottom: www.tnfish.org/FishIdentificationID_TWRA/TWRA_Sunfish_Identification_Key.htm.
Whichever it is, it shocked the heck out of me. I caught it in a gin-clear trout stream in the West Virginia mountains. Not what I was expecting... I have caught Warmouth in Georgia and Alabama and Rock Bass in Lake Ontario, but this didn't look like either one to me at the time. However, I won't argue with the experts. Rock Bass it is...