Abstract: The patterns of expressons and regulations in six isozymic systems (LDH, MDH, IDH,ADH, SDH and EST) were investigated in the early deveopmental stages (from unfertilized eggs to the stage of complcte yolk absoption) as well as six differentiated adult tissues (brain, eye, heart, muscle, kidney and liver) of silver carp. Isozymes were resolved by starch or polyacrylamide gel elctrophoresis and then detected by specific histochemical staining. Isozymes in adult silver carp apparently exhibit a tissue-specific expression.During the early developmenta period, both ADH and SDH genes seem to be inactive;the other four isozyme genes are active but exhibit different patterns of expressions.It is noteworthy, however that both LDH and EST genes in embryo from two pairs of silver carp parents taken from the same locality exhibit different patterns of expressions and regulations.We argued that there differences are related to the different complsitions of LDH and EST isozymes in unfertilized eggs of different female parents.Some related problems which ought to be further studied are also mentioned in the present paper.