This section is from the book "American Game Fishes", by W. A. Perry. Also available from Amazon: American Game Fishes: Their Habits, Habitat, and Peculiarities; How, When, and Where to Angle for Them.
Body elongate, not much elevated. Snout moderately prominent. Mouth rather large oblique, the maxillary reaching past front of eye. Cheeks with rather small scales, in about 7 rows. Scales of breast small. Palatine teeth few, rather large. Gill-rakers quite short, but stiff and rough; wide apart. Opercular flap very long (longer in the adult than on any other of the Sun-fishes except Lepomis megalotis), narrow, not usually wider than the eye. In the young the flap is variously shorter, but always narrow; lower margin of flap usually pale. Dorsal spines rather low. Color olive; belly largely orange red; scales on the sides with reddish spots on a bluish ground; vertical fins chiefly orange or yellowish; head with bluish stripes, especially in front of eye; no dusky blotch on last rays of dorsal and anal. Head (without flap) 3-in: length; depth 2 1-8. D. X, 11; A. Ill, 9; Lat. 1. 47. L. 8 inches.
This handsome Sun-fish is found in all ponds and streams east of the Alleghanies from Maine to Florida. It reaches a length of eight to ten inches, and is a pan-fish and a game-fish not to be despised. In Virginia and the Carolinas, it is the most abundant of the Sun-fish, and thrives wonderfully in millponds.