Gulf Flounder

The Gulf Flounder is a left-eyed flatfish found throughout the Gulf of Mexico and along the southeastern Atlantic coast of the United States. It is a close relative of the more widely known southern flounder and summer flounder, and is a popular target for inshore anglers. The species is best distinguished from its relatives by three prominent eyespots, each ringed with a lighter halo, arranged in a rough triangle on its upper side. Like other flatfish, it begins life as a symmetrical, free-swimming larva before undergoing metamorphosis, during which one eye migrates across the head so that both eyes end up on the upward-facing left side of the adult body.

Key field marks:

• Both eyes on the left side of a flattened, oval body
• Three dark, ringed (ocellated) spots arranged in a triangle on the upper body — the clearest identifying feature
• Mottled sandy brown to gray-brown coloration for camouflage
• Large mouth with sharp teeth
• Blind (right) side pale white

Look-alikes: Easily confused with southern flounder, which lacks the triangular eyespot pattern, and summer flounder, which has more numerous, less organized ocellated spots scattered across the body.

Gulf Flounder occupy shallow coastal and estuarine waters throughout the Gulf of Mexico, from Texas to Florida, and extend along the southeastern U.S. Atlantic coast to about North Carolina. They favor sandy or sand-mud bottoms in bays, tidal creeks, seagrass edges, and nearshore Gulf waters, typically in depths from just a few feet down to around 100 feet (30 m). Juveniles commonly use shallow estuarine nursery habitats before moving to somewhat deeper nearshore waters as adults. The species tolerates a range of salinities and can be found in brackish estuarine reaches as well as fully marine coastal waters.

Gulf Flounder are ambush predators that lie partially buried in sand or mud, relying on cryptic coloration to surprise passing prey such as small fish, shrimp, and other crustaceans. They are largely solitary and most active around dawn and dusk. Spawning occurs offshore during the cooler months of fall and winter, with pelagic eggs and larvae drifting inshore where juveniles settle into shallow estuarine nursery habitats. As they grow, individuals gradually move to deeper nearshore waters. The species shows the classic flatfish behavior of shifting position on the bottom and flicking sand over its body to enhance camouflage while waiting for prey.