American Plaice | Oceana Canada

Canadian Marine Life Encyclopedia

American Plaice

Hippoglossoides platessoides

Also known as

Dab, plaice, sole


Continental shelves of the Atlantic Ocean from the Arctic Circle to Rhode Island


Soft sandy or muddy bottoms

Feeding Habits

Ambush predator

Conservation Status



Order Pleuronectiformes (flatfishes); Family Pleuronectidae (right-eye flounders)


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When American plaice emerge from their eggs, they have a normal fish-shaped body. Like other flatfish, they develop their unique shape over time.  As they grow, their left eye starts to migrate over to their right side and their body begins to flatten. By the time they reach the juvenile stage and settle on the ocean floor, they will have assumed the classic flatfish shape. Their flattened body allows them to lie flush with the ocean floor and swim on their side, undulating just above the ground in search of their favourite foods. As adults, American plaice are known to be fairly adaptable to changes in prey availability; however they commonly feed on worms, molluscs, sea urchins, starfish, crustaceans and small fish. 

Male and female American plaice reach sexual maturity at different periods in their lives. Females usually reach maturity around eight to 11 years of age, while males reach maturity around three to six years of age. Spawning occurs in the spring between April and June. American plaice are batch or serial spawners, which means that they spawn multiple times during the season. Throughout the spawning season, one female can release between 400,000 and 1.5 million eggs. The number of eggs a female can produce during the spawning period depends on her size, with larger, older females producing the highest quantities of eggs. This spawning and fertilization occurs near the ocean floor, but once the eggs are fertilized they rise up to the surface of the ocean. The eggs will float along the upper layers of the water column, where they will hatch and begin to feed on zooplankton and other microscopic organisms. As they grow, they will begin the metamorphasis into their flat, adult body shape and settle onto the ocean floor.