Windowpane Flounder Identification Guide
Spot a windowpane flounder by its nearly round, paper-thin body that light can pass through.
Read the full Windowpane Flounder encyclopedia entry →
Key identification features
- Left-eyed flatfish with a nearly round to diamond-shaped body
- Body is so thin that light can pass through it when held up, giving it its name
- Large, widely spaced eyes paired with a small mouth
- Pale brown to olive coloring with scattered small dark spots
- Nearly translucent fins that ripple visibly along their edges when the fish swims
- Rarely exceeds 18 inches
Common look-alikes
- Summer flounder (fluke) has a thicker, more elongated body with prominent ocellated (ringed) spots, unlike the windowpane's plain thin translucent form.
- Four-spot flounder shows four distinct dark eyespots arranged in a square pattern that a windowpane flounder lacks.
- Winter flounder is a right-eyed species with a much thicker, more oval body, easily separated by eye side alone.
Where you'll see one
Windowpane flounder live over sandy and muddy inshore bottoms and estuaries along the U.S. Atlantic coast from Nova Scotia to Florida, often in shallow bays where their thin, disc-like body lies nearly flush with the seafloor.
Frequently asked questions
How do I tell a windowpane flounder from a summer flounder?
Windowpane flounder is much thinner and nearly round with a translucent body, while summer flounder is thicker, more elongated, and marked with distinct ringed spots.
What single trait most reliably identifies a windowpane flounder?
Hold it up to light if possible: its body is thin enough that light visibly passes through, a trait not shared by other similarly shaped inshore flatfish.