WordNet sense 1 (flesh of American flounder; important in the winter):

winter flounder

WordNet sense 2 (highly valued almost pure white flesh):

English sole

WordNet sense 3 (popular pale brown food flatfish of the Pacific coast of North America):

Parophrys vitulus

WordNet sense 4 (small European sole):

Solea lascaris

WordNet sense 5 (European flatfish highly valued as food):

Microstomus kitt

WordNet sense 6 (important American food fish in the winter):

blackback flounder, Pseudopleuronectes americanus