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. 

American plaice are an oval-shaped, right-eye flounder. This means that both of their eyes are on the right side of their flattened body. Interestingly, there are also left-eyed flounders, such as the Pacific sanddab. The right side of American plaices, or top-side, are a reddish- to grayish-brown that is generally uniform in colour. As juveniles, they have three to five large, dark spots along each edge of their body, which eventually disappear as they mature. The left side, or underside, of their body is white. They have a rounded tail, a relatively large mouth compared to their head, and a light-coloured, practically straight lateral line which runs from their gills to their tail. The lateral line marks a system of sense organs in their body that are used to detect movement, vibration and changes in pressure. Their large mouth and almost straight lateral line are features that can be used to distinguish them from other similar looking flounders. American plaice can grow to be more than 60 centimetres in length.