Fluke and flounder are both types of flatfish, recognized by their distinctive flattened bodies adapted for life on the seafloor. Many people often use these terms interchangeably, leading to some confusion about what distinguishes one from the other. While they share common characteristics as bottom-dwelling fish, there are specific differences in their physical traits, preferred environments, and culinary attributes.
Key Physical Characteristics
A primary visual difference between fluke and flounder lies in the placement of their eyes. Fluke, also known as summer flounder (Paralichthys dentatus), are “left-eyed,” meaning both eyes are located on the left side of their head when viewed from above. Conversely, many other species commonly referred to as flounder, such as the winter flounder (Pseudopleuronectes americanus), are “right-eyed,” with both eyes situated on the right side of their head.
Fluke possess a larger mouth and prominent, sharp teeth, reflecting their predatory feeding habits. In contrast, winter flounder have a smaller mouth with less visible teeth, indicative of their diet of small invertebrates. Fluke also tend to be lighter in coloration, often displaying light brown hues with distinct eye-like spots, and can rapidly change their skin color and pattern to blend with their surroundings. Winter flounder, while also capable of camouflage, generally appear darker, ranging from muddy brown to black.
Habitat and Geographic Distribution
Fluke, or summer flounder, are widely distributed along the western Atlantic Ocean, inhabiting waters from Nova Scotia in Canada down to Florida. During warmer months, typically from late April to September, these fish migrate into shallower coastal waters, bays, and estuaries. They prefer sandy or muddy bottom habitats. As temperatures drop in autumn and early winter, fluke move offshore to deeper waters along the continental shelf for spawning.
Winter flounder are found throughout the Atlantic coast of North America, extending from Labrador to North Carolina, with their highest concentrations from New England to New Jersey. Their movements are also seasonal; they migrate inshore to shallow bays and estuaries during the winter and early spring for spawning. Following spawning, they generally move back to deeper, cooler offshore areas in late spring and summer. These fish can be found on various bottom types, including sand, mud, and gravel substrates.
Culinary Uses and Flavor Profiles
Fluke has a delicate and mild flavor, often described as sweet with a clean finish. The flesh is white, firm, and flaky, making it a versatile option for various cooking methods. Common preparations include broiling, pan-searing, grilling, and poaching, and its fine texture also lends itself well to raw applications such as sushi or ceviche. Due to its low oil content, fluke fillets can dry out if overcooked, so gentle cooking methods are often recommended to preserve its tender quality.
Flounder, including species like winter flounder, also offers a mild and slightly sweet taste with a delicate, flaky texture. It may have a subtle brininess or a slight nutty undertone in its flavor profile. Flounder is a lean fish that adapts well to a range of cooking techniques, including baking, frying, and steaming. Its subtle flavor allows it to absorb seasonings effectively without being overpowered.