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 oblong, or elongate, the depth usually about 2 1-2-in. length; the head about 3; mouth pretty wide, the maxillary reaching nearly to middle of eye; lower jaw rather longest; fins rather small, the dorsal spines very low, the longest scarcely longer than snout; scales always small, about 46 in the course of the lateral line; opercular flap short and small, less than eye, broadly margined with pinkish, the black confined to the bony part of the flap. Colors extremely variable, the prevailing shade usually green, with a strong brassy luster on sides, becoming usually yellow below; often nearly all deep green, often with the blue predominating, sometimes in northern specimens nearly black; each scale usually with a sky-blue spot, and more or less of gilt-edging, which gives an appearance of pale lines along the sides; besides the blue spots, some specimens, usually young or half-grown ones, are crossed by vertical bars of a brassy olive, or sometimes almost black color; many adults are further marked by sprinklings of black dots; vertical fins marked with green and blue, the anal almost edged in front with pale orange; ventrals usually yellowish; iris red; cheeks with narrow wavy stripes of bright blue; usually a round black spot on last rays of dorsal and anal behind-the latter, and sometimes both, obsolete. A species extremely variable both in form and coloration, yet easily recognizable at sight.
This is a small but active and voracious sun-fish that generally makes his presence felt whenever an angle-worm is dropped in his vicinity. It is found in all waters between the Rocky Mountains and the Alleghanies, and from Michigan to Texas. Wherever it is found it is abundant.
The other species of Lcpomis are either scarce or small, or else wholly confined to the lowland waters of the South, and it may not be necessary to refer to them farther.
Closely related to these are some small species of other genera of Sun-fishes, found only in the lowland waters of the Eastern States from Massachusetts to Florida. These are the Banded Sun-fish, Mcsogonistias chaetodon (Baird), straw-color, with jet-black cross-stripes, too small for a food fish, but too handsome to be overlooked by any angler. It is common only in the lowlands of the Delaware River.
Enncacanthus obcsas and gloriosus, with shining spots of brown and blue, have a wider range, but reach no larger size, while AcantharcJius promotis, the Mud Sun-fish, dark green, with darker stripes, much resembles the Red-Eye or Rock Bass.