The process of oogenesis of C. chalcoides living in Lake Tödürge was histologically studied from monthly samples during April–November 2000. The process was divided into five stages (previtellogenic, cytoplasmic growth, vitellogenic growth, yolk oocyte and mature oocyte). Oocytes of the previtellogenic and mature phases were mainly seen in July and May, respectively. Oocytes and nuclei diameters were observed between 38–1470 μm and 29–270 μ m until ovulation. C. chalcoides is thus considered to be synchronous. The ovulation period started in late May and ended in the beginning of July.