## 3 Results
### Gonad Histology  
An almost identical number of females and males were detected in the control treatment (Table 4). Nevertheless, the number of females was significantly higher than the number of males in all extract-treated groups with the best sex reversal in the T3 treatment, indicating that feminization is a dose-dependent process. The oocyte development was divided into four stages (primary growth, cortical alveolus, vittogenin, and mature oocyte). Oocyte diameters were observed to vary between 0.54-0.75 mm, that highest was in T3 (Table 4). Histological and morphological investigations of the gonads revealed no intersex fish in all groups.  
The control treatment was often immature oocytes and in primary growth (Figure 1a). Oocytes developed from the primary growth stage to the cortical alveolus stage with increasing doses from 5 to 10 g\({}^{-1}\) kg (Figure 1b,c). Oocytes exhibited maximum growth, vittellogenic and mature oocyte in the group receiving 15 g\({}^{-1}\) kg of plant extract (Figure 1d). The oocyte's growth was similar in the teleosts. In most of the teleosts, the growth of oogenesis might be in four, five, six and eight phases. The oocyte's development in the zebrafish was manifested in a series of variations, and their division was during four stages. Throughout the oocyte growth, the oocyte was enlarged due to proteolysis and hydration of the yolk protein. The vittelling envelope started to form in the cortical alveolus stages and develop in the vittellogenic stages, and was obviously detected in the mature oocytes.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Reproductive Indices** & **T0 (Control)** & **T1 (5 g\({}^{-1}\) kg)** & **T2 (10 g\({}^{-1}\) kg)** & **T3 (15 g\({}^{-1}\) kg)** \\ \hline egg diameter (mm) & 0.03 \(\pm\) 0.54 \({}^{\text{c}}\) & 0.02 \(\pm\) 0.61 \({}^{\text{b}}\) & 0.01 \(\pm\) 0.65 \({}^{\text{b}}\) & 0.03 \(\pm\) 0.75 \({}^{\text{a}}\) \\ \hline survival of larvae & 2.3 \(\pm\) 85.0 & 3.2 \(\pm\) 90.2 \({}^{\text{b}}\) & 96.1 \(\pm\) 2.7 \({}^{\text{b}}\) & 97.2 \(\pm\) 2.3 \({}^{\text{a}}\) \\ \hline absolute fecundity & 32.62 \(\pm\) 479.75 \({}^{\text{c}}\) & 66.30 \(\pm\) 535.22 \({}^{\text{b}}\) & 52.7\(\pm\)566.35 \({}^{\text{b}}\) & 599 \(\pm\) 56.3\({}^{\text{a}}\) \\ \hline Gonadosomatic index & 1.15 \(\pm\) 0.05 \({}^{\text{c}}\) & 1.76 \(\pm\) 0.04 \({}^{\text{b}}\) & 2.48 \(\pm\) 0.02 \({}^{\text{b}}\) & 2.85 \(\pm\) 0.03 \({}^{\text{a}}\) \\ \hline Length of larvae (mm) & 5.1 \(\pm\) 0.05 \({}^{\text{c}}\) & 5.5 \(\pm\) 0.03 \({}^{\text{b}}\) & 5.9 \(\pm\) 0.02 \({}^{\text{b}}\) & 6.6 \(\pm\) 0.02 \({}^{\text{a}}\) \\ \hline Weight of larvae (mg) & 1.2 \(\pm\) 0.020 \({}^{\text{c}}\) & 1.78 \(\pm\) 0.025 \({}^{\text{b}}\) & 0.056 \(\pm\) 1.90 \({}^{\text{b}}\) & 2.1 \(\pm\) 0.065 \({}^{\text{a}}\) \\ \hline Sex ratio (\%M:%F) & 48.88:51.12 & 21.43:78.57 & 15.44:82.56 & 12.77:87.23 \\ \hline \end{tabular}  
* Results are given as mean \(\pm\) standard deviation. The different letters in each row represent significantly different (\(p<0.05\)).  
\end{table}
Table 4: Reproductive effects of _Vitex agnus-castus_ extract on broodstock of zebrafish.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Treatments** & **SR (\%)** & **SGR** & **FCR** & **CF** & **BWG** \\ \hline
**T0 (Control)** & 89.5 \(\pm\) 1.1 \({}^{\text{a}}\) & 0.023 \(\pm\) 0.001 \({}^{\text{a}}\) & 0.98 \(\pm\) 0.05 \({}^{\text{a}}\) & 3.816 \(\pm\) 0.014 \({}^{\text{a}}\) & 252.962 \(\pm\) 17.71 \({}^{\text{a}}\) \\ \hline
**T1 (5 g\({}^{-1}\) kg)** & 100 \(\pm\) 1.7 \({}^{\text{a}}\) & 0.030 \(\pm\) 0.001 \({}^{\text{b}}\) & 0.97 \(\pm\) 0.02 \({}^{\text{b}}\) & 3.892 \(\pm\) 0.013 \({}^{\text{b}}\) & 425.172 \(\pm\) 21.55 \({}^{\text{b}}\) \\ \hline
**T2 (10 g\({}^{-1}\) kg)** & 100 \(\pm\) 1.72 \({}^{\text{a}}\) & 0.033 \(\pm\) 0.002 \({}^{\text{b}}\) & 0.83 \(\pm\) 0.02 \({}^{\text{c}}\) & 4.223 \(\pm\) 0.016 \({}^{\text{c}}\) & 541.502 \(\pm\) 33