Ovarian structure and oogenesis in King Tiger Pleco, L333, Hypancistrus seideli, (Siluriformes: Loricariidae) from the Amazon region.

In this study, we describe the ovarian structure and oogenesis up to the final maturation of oocytes of Hypancistrus seideli. A total of sixty females were used for gonadal analysis and subsequently submitted to light and scanning electron microscopy analyses. Four maturation stages were defined: immature, maturing, mature, and spawned. The oocytes were classified into four stages (I–IV), and the presence of atretic oocytes and post-ovulatory follicles was demonstrated. During oocyte development, changes were observed in color, size, and shape, as well as in the formation of the follicular complex. These results may support reproductive management in captivity, since the species has great commercial importance in the international ornamental fish market and lacks established reproductive protocols in aquaculture. To our knowledge, this is the first morphological characterization of oogenesis in this species, providing original and detailed data that may contribute to the development of captive breeding protocols and to reducing pressure on natural stocks.