Due to the growth in Aquatic system and their health and economic well being of forming system is very important.Hypophthalmichthys molitrix (silver carp) is one of the breading fish of cyprinus family that feed from phytoplanktons in water.Howere environmental condition of breading fileds mount be consider to obtain a optimal statu and fertilization of them to growth of biomass and diversity of phytoplanktons for growth silver carps. Shoshtar city is in east North of khozestan province with sustainable water rivers to breading of warm water fish.This study was started on biomass effect and density of phytoplankton on silver carp fry with 2.5 gr in polycalture farms. The stady was started from July 1391 and up to 45 days in Fourth stages of physical and chemical parameters of water Do, Temperatur, Electrical conductivity, Nitrate, phosphate,TDS, pH and chlorophyll a (biomass) as well as measurement and weight charachteries indetify and determine the length juveniles and phytoplankton concetrion with three replicates per treatment was carried out.The results showed that weight gain during the second trail of the same treatment were compared to the control treatment. Phytoplankton biomass based to measurement of chlorophylla (0.008±0.009 mg/l) showed and increasing in comparsion to the control treatment (p≤ 0.05). in general juvenile increased during treatment and had more weight show the control group.The amount of double fertilization treatments of silver carp juveniles increased in length and weight more than the control (p≤0.05). In general environment parameters expect dissolved oxygen, Ec and TDS were not significantlly different.