In this investigation rainbow trout growth rate, blood factors, food valuables were studied in fresh and brackish water. For this reason, some 180 young rainbow trout with weight of 47.10 0.1g were released in 6 polyethylen basins with capacity of 1.5m3 water. Two treatments with three repetitions were done. At the time of testing, feeding for each repetition was done with trend to water degree and fish biomass. The biometery from each fish was done and recorded every 15-day. After 126 days, the live fishes were transferred to libratory and after biometry, their weight and length; all blood desired factors were measured with taking blood from their hearth. Also chemical analyzed of their muscle was done. The results showed that fish growth in brackish water from after third biometry process showed significant increase. With due attention to other treatment amount of WBC, Hb, HCT, MCV, MCH, MCHC, Lymp Throm and K+ in brackish water showed significant increase compared to fresh water (P<0.05). Also chemical analyze test showed that the amount of fat, dry material in brackish water fishes had a significant difference (P<0.05). Wet amount of fish’s muscle in brackish water was higher compare to freshwater and had significant differences (P<0.05).