Plasma Levels of Sex Steroids (Testosterone, Progesterone and 17β-Estradiol) in Rohu Carp Labeo Rohita Broodstock From Khuzestan, Iran

Sex steroids (testosterone, progesterone and 17β-estradiol) play important roles in controlling reproduction and sexual maturity in teleosts. the aim of the present study was to evaluate the seasonal changes of these steroids in rohu labeo rohita. forty gravid females and males l. rohita reared in different seasons (spring, summer, autumn, winter) were caught by a net with 1 cm mesh from earthen ponds of aquaculture research institute, in south of iran. the highest levels of 17β-estradiol (122.8±17.73 ng ml^-1 ), testosterone (0.11±0.003 ng ml^-1 ) and progesterone (0.86±0.01 ng ml^-1 ) in female fish were recorded in autumn. in addition, the highest concentration of testosterone in male was determined as 0.84±0.003 ng ml-1 in autumn. the mean value of dissolved oxygen in four seasons (spring, summer, autumn, and winter) were 9.21±0.77, 8.36±0.51, 10.41±0.9 and 13.14±0.72 mg l^-1 , with temperature 25.47±1.07, 29.88±1.42, 20.23±0.69 and 14.63±0.47 ◦c, respectively. therefore, it can be inferred that progesterone was considered as the critical index for seasonal breeding selection. there was an appropriate condition in the mid winter for broodstock selection and breeding of fish with hormones manipulation.