Warmouth sunfish are not as deep bodied as bluegill or redear sunfish. They can change from light to dark brown very quickly to blend in with their surroundings. They have large dark blotches on their sides and back which do not normally form an organized pattern. Younger fish can sometimes have a purplish sheen to their sides. Warmouth sunfish also have a very large mouth and red eyes. They have alternating dark and light lines on the side of their cheek radiating away from the eye that extend to the rear of the gill cover. These lines are not blue or green like those of green, longear, or pumpkinseed sunfishes. Warmouth sunfish also have a light colored margin to the fins that can be white, orange, yellow, or red. The rock bass is similar in appearance but has 6 anal fin spines compared to the 3 that a warmouth sunfish has. Rock bass have a teardrop under the eye, no radiating lines on the cheek, and a black margin to the fins. Breeding male warmouth sunfish have gold or light blue speckles on their sides and a faint red spot at the rear base of the dorsal fin.