Fourspot Flounder

(Hippoglossina oblonga)

Overview

The fourspot flounder, named for the four dark, circular splotches on its side, belongs to the larger group of flatfishes, some of the coolest fish in the ocean! They may not look that remarkable while lying on the sand and holding still, but these species undergo a wild transformation as they develop.

As larvae, fourspot flounder look like most other fish larvae. They're symmetrical, with an eye on either side of their heads, and they swim upright, like salmon, mullet or clownfish. Then, a metamorphosis begins. Bones in the flounder's head bend—practically disappearing in some cases—and reform as one eye migrates to the other side. The jaws twist and warp to align at a better angle for catching prey from below. Within a few weeks, the fourspot flounder has become an asymmetric fish best suited for lying sideways on the seabed. Talk about growing pains!

And if lying partially buried in the sand isn't inconspicuous enough, the fourspot flounder is also great at camouflage. Though its underside is usually pale white, its top side is densely covered with chromatophores (special cells that help the fish change color).

The best chance guests have of seeing these flounders at the National Aquarium is to witness them swimming in their pillar-shaped habitat in Living Seashore or to scan the sandy bottom for two small lumps (the fish's eyes) poking out.

Quick Facts

Learn more about the fourspot flounder! Did you know it is one of many left-eyed flatfish species? This means its right eye migrates to the left side of its body, leaving the right side as the blind side. Some other flatfish species are right-eyed.

The fourspot flounder is found along the East Coast of the U.S., from the Gulf of Maine south to Florida, in depths of up to 300 feet.

Fourspot flounders are mostly piscivorous, preying on smaller fish like silversides, sand lance or juvenile cod. They've also been known to eat invertebrates like amphipods, crabs, octopus and squid.

The fourspot flounder is a relatively small flatfish, typically reaching 10 to 12 inches in length.

Though not targeted by fisheries, fourspot flounders are often caught as bycatch. They are somewhat protected thanks to bycatch reduction methods and seasonal closing of certain fishing grounds. Though more studies are needed, their population is considered stable.

Sharks and other carnivorous fish prey on the fourspot flounder.

Subscribe To Our Newsletter Sign up to receive updates on animals, news and events.