Along the Texas Gulf Coast, southern flounder can be found from Brownsville to Sabine Lake in pure fresh water, out to full-strength seawater off the coast, although most studies show that they are most common at moderate salinities.

Most research indicates that male flounder stay in offshore waters year-round. Male Flounder are smaller, seldom growing larger than 10 to 12 inches, but the females grow much larger and move longer distances. Females may reach 23 inches long, and spend most of the year in inshore waters, only migrating offshore during October to December to spawn. Excellent catches of flounder can be made during this period.

Female southern Flounder spawn several times during their short annual spawning period, producing about 100,000 eggs each spawn. Spawning seems to be triggered by water temperatures of about 56 degrees F and usually occurs between 5 and 9 a.m.

After hatching, larval southern Flounder grow most rapidly in highly saline waters. Young flounder begin to appear along the Texas Gulf Coast inshore estuaries between January and April, and range 1/4 inch to 2 inches in length. Like other fish, flounder hatch with one eye on each side of the head. Movement of the right eye to the left side of the head begins when the fish is 1/3 to 1/2 inch long and is complete when the fish is 3/4 inch to 1 inch long. At this same time, the left side develops its dark color and the right side turns white.

After hatching, southern flounder larvae eat microscopic floating animals (plankton). As juvenile fish, they eat small bottom animals. At about 6 inches long, they adopt their adult diet of fish and shrimp.

In Texas, researchers have noted that the southern flounder is the dominant predator of shrimp in the spring, and that most of its diet is anchovies, mullets, shrimp, menhaden (pogies) and croakers. As Flounder get larger they don’t eat larger fish, they just eat more small ones.

Female southern Flounder grow more rapidly than males. A research project along the Texas Gulf Coast did not find a male southern flounder over 13.5 inches long. Another study in Georgia showed no males more than 16 inches long, and research in Texas showed no males over 12.8 inches long. Female Flounder grow quickly their first two years; then their growth slows. Approximate average lengths at each age for females are: Age 1, 10 inches; Age 2, 16.7 inches; Age 3, 18.8 inches; Age 4, 19.6 inches; Age 5, 20 inches; Age 6, 20.4 inches; and Age 7, 20.5 inches. Few females live beyond seven years old and almost no males live past three years old.

Flounder are considered “ambush predators.” Instead of actively pursuing their prey, they lie in wait in areas that are likely to concentrate or disorient small fish or shrimp. From their position on the bottom, Flounder pounce on these animals as they move by.

Because of their feeding habits, large numbers of Flounder will concentrate in good ambush areas. Especially productive are current-swept points and channels that serve as choke points for tidal currents.

Southern Flounder take live bait, jigs, or even spoons that are fished near the bottom. Because their mouth opens side-to-side, rather than vertically, small hooks will produce more hook-ups than large hooks.

Flounder may also be gigged with a pronged spears (called gigs) in shallow waters at night by fishermen using lanterns for illumination or from boats equipped with lights on the front.. Firm sandy bottoms are preferred for easy wading. Gigging is most successfully conducted on a rising tide and in clear water.

Currently, the daily recreational limit on southern Flounder is 10 per day.