In order to reduction of adverse effects of sexual maturation on growth and survival of rainbow trout, production of allfemale triploid were investigated by means of early heat shock on eggs which fertile by masculinized male’s (Neomale) sperm. Fish ploidy level was determined by erythrocyte size measurement and confirmed by gill nucleolus (NORs) counting as well as chromosome number. Sexual ratios and gonad development were determined by histological studies. Final results show that progenies which produced by mating sex-reversed males and normal females were totally female (100 %). Also applying early heat shocks (26.5° C lasting 20 min, 20 min after egg fertilization) were induced triploidy about 80 % in fishes. All-female triploids, show some structural abnormalities like erythrocyte amitosis and nuclei segmentation in their blood smears. The objective of this research was accurate determination of these alterations and their probable effect on erythrocyte functions in our samples.
