The eyes and mouth of the Mud Sunfish are large, and the upper jaw extends below the eye.
They are one of Delaware’s least colorful sunfishes. The body is reddish brown on top and pale brown on the belly. There are five distinct lines located along the fish's sides.
Its ear flap has a black spot, sometimes orange in larger specimens.
Similar in appearance to the Rock Bass, the Mud Sunfish can easily be distinguished by its round tail and its brown eyes.