Physiological and histopathological effects of 21 days fadrozole exposure. (A) Cumulative fecundity of zebrafish during the 16 days acclimation period prior to treatment and within the subsequent 21 days exposure period. A statistically significant reduction in mean egg numbers was observed upon exposure to 1.0 µg/L and 10.0 µg/L fadrozole treatment as compared to the control group in the exposure phase. (B) The cumulative mean number of fertilized eggs within the 21 days exposure period was observed to be significantly reduced in the 1 µg/L and 10 µg/L fadrozole conditions. (C) Fertilization rate of zebrafish after the exposure to fadrozole for 21 days was observed to decrease significantly in a concentration-dependent manner. (D) Plasma VTG content was significantly reduced at 10 µg/L fadrozole treatment compared to control fish. Statistically significant differences were calculated by ANOVA, followed by Dunnetts post-hoc t-test with significance levels set at *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001); n = 2 fish/replicate, 4 replicates/treatments. (E) Weight of male and female zebrafish exposed to fadrozole recorded a significant increase in the weight of female zebrafish and a decrease in weight for male zebrafish. (F) Length of male and female zebrafish exposed to fadrozole recorded a significant increase in the length of female; a no significant change was observed for male zebrafish. (G) Section of control ovary showing no pathological alterations. (H) Representative histopathological observation of female ovary at 10 µg/L fadrozole treatment showing mild oocyte atresia and membrane folding (Arrows: membrane folding; Asterisks: atretic oocytes).