The yellowtail flounder is a wide
flatfish with an ovoid body, about half as broad as it is long. The name "yellowtail" comes from the distinctly yellowish color of its
fins (including tail fin); the fish's upper side is reddish brown with irregular "rusty" spots, while the underside is white with a yellow
caudal peduncle (area between body and tail). Being a right-eyed flounder (of the family
Pleuronectidae), both its eyes are on the right side of the fish's body, though the eyes are symmetrical just after hatching. It is thinner than other flatfish. The fish's head is approximately a quarter as long as the total body and is scaly. The eye's diameter is approximately one fifth the length of the head. The yellowtail flounder has a prominent lower jaw with broad lips, about as long as the eye. The scales are ciliated (having hair-like protrusions) and appear on the head as well. The teeth are small. Its
dorsal fin, comprising about 80
rays, begins over the eye and has longer rays near the middle. The
anal fin has a similar outline, but is only composed of about 60 rays. Relative to other flounders in the
Gulf of Maine, the yellowtail flounder has a narrower and more concave head, with a pointier snout. == Distribution and habitat ==