Sea were investigated by stomach content analysis of 357 fish collected monthly (October 2003 to April 2004) in the commercial catch. The diet consisted mainly of fish dominated by Atherinidae (58%), with Atherina boyeri being the dominant prey item based on numerical percentage. The next major food group was Gobiidae (26%), followed by Clupeidae (11%), Cyprinidae (3%), and Mugilidae (1%). Based on frequency of occurrence, A. boyeri was the main prey in the stomach of Caspian marine shad (Fi = 57.7%), with an important species index (ISI) of 59.7%. The fish fed on a wider variety of food items during November, December and February than during other months. The lowest feeding activity was recorded in October and January. The gastrosomatic index (GaSI) ranged from 0.3% to 27.7% with monthly variations increase in February and March coincides closely with spawning season and energy preservation for gonadal development.