Six stages of the female Brachyhypopomus gauderio ovary were described. Two of these belong to the primary growth phase: primary growth one nucleolus (PGon) and primary growth peri nucleolus (PGpn), during which the oocytes are small in diameter and free of cortical alveoli. The third, fourth, and fifth stages represent secondary growth, characterized by the presence of cortical alveoli, which increase in number as the stages progress. This phase is called vitellogenesis and is divided into three stages: primary, secondary, and tertiary vitellogenesis. The final stage, known as periovulatory (PO), is marked by the oocytes being fully filled with cortical alveoli and the disappearance of the nucleus, indicating that the eggs are ready to be laid.