Mummichog

This is a tough one. The angle of the photo and fin placement at first made me think mudminnow or killifish, but the light edges on those fins remind me of green sunfish. Sunfish can relax those spiny dorsal rays so that they may be hard to see, but I can't see any evidence of the spiny dorsal in this photo. Sally, do you have any other images? Here is a key to Maryland freshwater fish that might help you narrow it down:
http://dnr.maryland.gov/streams/pdfs/fis...