Pesticides used to protect plants and animals against the competition of unwanted insects, diseases, and weeds, and pests play a delicate role in living systems. It has adverse effects on the environment and health. The most adverse effects of pesticide derivatives are the reduction in biodiversity, water pollution, and health risks. Mancozeb is an ethylene bis dithiocarbamate (EBDC) pesticide containing manganese and zinc. These pesticides are included in the fungicide group because they are used for treating fungal diseases. In this study, the structure of oocytes developing in female zebrafish exposed to different doses of mancozeb (5 mgL−1, 7.5 mgL−1) was examined. Compared with the control group, it was determined that the number of developing oocytes reduced in the experimental groups. There was a significant increase in atretic oocytes, an increase in the level of degenerate oocytes in a dose-dependent manner, and deformation in oocytes became prominent.