The aim of the Biochemical study, the mobilization of metabolism and minerals in gonads during breeding cycle of fishes were studied.With the view to investigate breeding cycle, growth period and nutritive value of edible fishes, two species from Sillaginidae and Sciaenidae family were selected. The breeding cycle and growth rate are also under influence of the environmental factors. Jodia village of Jamnagar district (Gujarat, India) was selected for the research site. the main objectives of the study were 1) To study the mobilization of metabolites in gonads during breeding cycle of selected fishes. 2)To study the mobilization of minerals in gonads during breeding cycle of selected fishes. Various metabolites like glycogen, total lipids, cholesterol and protein have been estimated. The minerals such as sodium, potassium, phosphorous, calcium, magnesium and iron contents in testis and overy were also determined by various biochemical techniques.