Rancidity - The oxidation of the natural oil in the fish, making the fish unpalatable.
Red Tide - A reddish-colored carpet of algae that appears below the surface of the
sea and is eaten by clams, mussels and oysters. The algae secrete a
substance that can be toxic to humans. Fishing grounds are closed when
red tide occurs, preventing the harvest of any contaminated shellfish.
Roe - Most fish species grow their eggs in a sac in the abdomen, and the roe
of some species is considered a delicacy in various countries. Sturgeon
roe, or caviar, is the best-known and most expensive in the U.S., but
cod, herring, mullet, pollock, salmon and shad all produce roe prized
by various regional and ethnic groups.
Roundfish - Refers to physical shape of the body of the fish, and is more a
convenient way to group all fish other than those in the flatfish
family than a scientific classification. (See Flatfish).