"The bluegill is noted for the darkened spot that it has on the posterior edge of the gills and base of the dorsal fin. The sides of its head and chin are a dark shade of blue. It usually contains 5-9 vertical bars on the sides of its body, but these stripes are not always distinct. It has a yellowish breast and abdomen, with the breast of the breeding male being a bright orange. The bluegill has three anal spines, ten to 12 anal fin rays, six to 13 dorsal fin spines, 11 to 12 dorsal rays, and 12 to 13 pectoral rays. They are characterized by their deep, flattened, laterally compressed bodies. They have a terminal mouth, ctenoid scales, and a lateral line that is arched upward anteriorly. The bluegill typically ranges in size from four to 12 inches, and reaches a maximum size just over 16 inches."

Source: Wikipedia: http://en.wikipedia.org/wiki/Bluegill, accessed on 8/3/12.