Fish roe are fish eggs that have not been brined. Caviar is a term that describes the brining process itself of roe (not a name of a particular type of fish). While there is no official international law, there is rather an understanding that for labelling purposes only the fish species Sturgeon (the oldest type of fish used for caviar) can be labelled as Caviar. Roe from any other species that has been caviar brined must list the species name before the word caviar i.e. Salmon Caviar.