Windowpane Flounder

The windowpane flounder is a left-eyed flatfish in the family Scophthalmidae (turbot family), found along the Atlantic coast of North America from the Gulf of St. Lawrence to Florida. It is named for its extremely thin, nearly translucent body, thin enough that light can pass through it, giving rise to the "windowpane" name. Unlike many bulkier flatfish, windowpane flounder have an almost circular, disc-like outline. The species is common in shallow coastal and estuarine waters and, despite modest size, is a familiar species in coastal trawl surveys. Its delicate, translucent body and rounded shape make it one of the more visually distinctive flatfish along the U.S. East Coast.

• Nearly circular or diamond-shaped, very thin, almost translucent body
• Eyes on the left side, set relatively far apart
• Upper side is light brown to olive with scattered darker spots and blotches, sometimes faint eye-like markings
• Body is thin enough that internal structures or light may be faintly visible through it
• Long-based dorsal fin beginning in front of the eyes, with the first few rays free of membrane
• Adults typically reach 20-35 cm

Its rounded, disc-like shape and translucent thinness separate it from summer flounder, which is thicker-bodied and more elongated, and from winter flounder, which is opaque and more oval.

Windowpane flounder are found along the Atlantic coast of North America from the Gulf of St. Lawrence and Nova Scotia south to Florida, with greatest abundance in the Mid-Atlantic and southern New England region. They inhabit shallow coastal waters, bays, and estuaries on sand or sand-mud bottoms, typically from just a few meters to around 60 meters deep. The species tolerates a range of salinities and is commonly found in nursery habitats close to shore, including areas near river mouths and inshore flats.

Windowpane flounder are relatively inactive, bottom-resting fish that rely on their thin, translucent bodies and mottled coloration for camouflage against sandy or muddy substrate. They feed opportunistically on small fish, shrimp, and other invertebrates, often ambushing prey from a partially buried position. The species spawns over an extended period spanning spring through fall depending on location, releasing large numbers of small, buoyant eggs that drift with coastal currents. Because they favor shallow coastal and estuarine habitats, windowpane flounder often serve as an indicator species for the health of nearshore nursery environments.