Adult yellow perch are usually golden yellow; young are usually more whitish. There are 6 -- 8 dark vertical bars on the sides of these fish. Their eyes are green to yellow. They have a spiny dorsal fin with 12 -- 14 spines and a second dorsal fin with 12-13 soft rays plus 2-3 spines. There is usually a blackish blotch on the membrane between the last 3 or 4 dorsal spines. Their bottom fin has 2 spines and 7-8 soft rays. The lower fins of adults are usually tinged yellow or red; this is especially noticeable on males during breeding season. The lateral line is prominent and curved with 51-61 scales along it. Yellow perch have rough feel because they have ctenoid scales.
Adult yellow perch usually grow 10 to 25.5 cm in length, occasionally they can reach 35.6 cm, but these are older fish than most. There is sexual dimorphism in yellow perch. Females grow faster and reach a greater ultimate size than males. There is a 2.5 cm length difference in seven-year-old fish. The growth rate of perch varies greatly from one body of water to another.