In this survey, fishes were obtained from four localities: Assiut as a control and Beheira, Alexandria and Kafr
EL-Sheikh; three farms from each governate as farmed monosex produced using Methyltestosterone (MT). Serum
MT, total antioxidant capacity (TAC), malondialdehyde (MDA), and total peroxides (TPX) were estimated, followed
by calculation of oxidative stress index (OSI). MT concentration in the serum of fishes farmed at Assiut showed no
detectable levels of hormonal residues, while the monosex farms showed high levels of MT concentration in the
serum of the sampled fishes. In comparison with control fishes of Assiut farms, serum TAC levels of monosex fishes
collected from farms of Beheira and Alexandria were significantly lower. Serum TPX content of the monosex fishes
obtained from Alexandria farms were significantly higher than the wild fishes obtained from Assiut farms. Calculated
from ratio of serum TPX content and TAC concentration, OSI illustrated a significant difference between control
fishes collected from Assiut and monosex fishes collected from Beheira. Although few significant changes were
found in the examined oxidative stress endpoints, the results of this work put our foot in the beginning of road to link
hormonally sex reversal practice with oxidative stress induction, and provocative for other researchers to invade this
field of research more deeply utilizing more specific relevant markers and cutting-edge techniques.