Flat Not Flounder: The Many Species of Flatfish That Live in Texas Bays and How to Tell Them Apart

The sun begins to sink beneath the horizon as you pull up to the boat ramp. You watch as anglers from the day are hauling out their skiffs and throwing their freshly fileted fish carcasses to the pelicans standing close by in wait. As day turns to night, out of towners and new anglers watch in confusion as you launch your skiff into the bay. Longtime locals, however, know exactly what you’re doing and what you’re targeting. The sought-after missing element from their Texas grand slam, is the Southern Flounder. These flatfish play an important economic and cultural role here in Texas. The exhilaration of being able to harvest this species with its flaky white filets make it an irresistible catch for Texas anglers and gig fisherman alike.

For nearly 50 years, TPWD’s Coastal Fisheries Management teams have been conducting fisheries monitoring of flatfish along the Gulf coast of Texas. Unfortunately, sampling data has shown a steady decline in population trends for Southern Flounder since sampling began in the mid-seventies. Thus, effectively managing this population is crucial to ensure anglers have the opportunity to fish for flounder for generations to come. The sampling data collected by coastal fisheries biologists is used when considering management options or regulation changes. Thus, the accuracy of this data is of the utmost importance.

Southern Flounder are the most widely known flatfish species in the Gulf of Mexico (GOM), largely due to their size and abundance in estuaries. However, flatfish species are incredibly diverse within the GOM and TPWD fisheries staff encounter a plethora of species that, to the untrained eye, can be nearly indistinguishable from the highly sought after Southern Flounder at juvenile stages. Because of this, it is of great importance that fisheries management staff keep a keen and professionally trained eye when it comes to flatfish identification. Three of the most encountered flatfish in Texas include the Bay Whiff, Blackcheek Tonguefish, and Hogchoker.

Of these three species, the Bay Whiff is the most closely related to (and most difficult to distinguish from) Southern Flounder—both belonging to the family Paralichthyidae. This species is frequently captured in trawl and bag seine sampling gears and tends to be more than twice as abundant as juvenile Southern Flounder captured in the same sampling gears. While an adult Bay Whiff can only grow to about eight inches in length, they can be extremely difficult to discern from Southern Flounder at the juvenile stage. TPWD biologists discern these two species from one another by paying close attention to the lateral line. The lateral line on a Southern Flounder has a steep arch towards the head while that of the Bay Whiff is relatively flat in comparison. But don’t fret—given the Bay Whiff’s small maximum size, there is no need to worry about confusing these two species under the dim glow of a gigging lamp.

Tonguefish are another frequently encountered flatfish found here on the Texas coast. Tonguefish belong to the family Cynoglossidae, which consists of individuals that are elongate and oval in profile, with eyes on the left side of the head (similar to both Bay Whiff and Southern Flounder). Specifically, the Blackcheek Tonguefish is commonly captured in trawl and bag seine samples and rarely exceeds seven inches in length. As the name would imply, the Blackcheek Tonguefish has a slender and elongated body closely resembling the shape of a human tongue and notably different from the body shape of the juvenile Southern Flounder. Also, as the name would imply, this species has a prominent dark spot on the ocular-side of its operculum, better known as its cheek.

Hogchoker belong to the sole family Achiridae, which are comprised of flatfish that have both eyes on their right side. The Hogchoker has an oval, almost egg-shaped profile, with light and dark spots and lines covering the entire ocular or frontal side of its body (Figure 4). Its name comes from a time (long ago) when these fish were included in the feed of farmed hogs. Farmers claimed that this species would suction to the pig’s mouth and cause them to choke. Although they are much easier to distinguish from the Southern Flounder than some of our other flatfish, TPWD biologist, nonetheless, are trained to correctly identify and record data on this species as well as their more sought-after cousins.

Overall, these “other” flatfish species are just a few of the species found in the GOM along the coast of Texas. While these lesser-known species likely won’t ever reach a large enough size to warrant the attention of local anglers, they do play important roles within the estuarine food webs of the Texas coast. Properly identifying them and distinguishing them from southern flounder within our fisheries monitoring dataset is crucial to our ability to effectively manage the Southern Flounder we know and love. So, the next time you gaze into the dimly lit shallows beneath your gigging lantern, remember the many species of lesser-known flatfish that you may never see. For TPWD biologists, there’s no “floundering” around when it comes to their importance in our coastal ecosystems.