Megrim is a marine flatfish — Lepidorhombus whiffiagonis or L. boscii — of the family Scophthalmidae, valued commercially in the north-east Atlantic and western Mediterranean, where it is sold fresh and frozen. Its flesh leans dry, so frying in fat suits it best; the skin serves as a source of collagen and gelatin. Like other lean whitefish it is highly perishable, demanding rapid chilling after capture and an unbroken cold chain to the consumer; hygienic filleting, correct species labelling and traceability help prevent substitution fraud.