Testicular structure and development of germ cells of Hypophthalmus marginatus Valenciennes 1840 (Siluriformes: Pimelodidae).

The present study was conducted to assess the testicular structure and germ cell ultrastructure of Hypophthalmus marginatus during spermatogenesis. Semen and sections of the mid-region of the testis were collected, processed, and analyzed using optical and electron microscopy. Macroscopically, the testes of H.

Inappropriate management conditions, especially for the regressed class, are related to sperm quality in Prochilodus lineatus.

The aims of this study were to evaluate the characteristics of the reproductive classes and semen quality in curimbatá (Prochilodus lineatus) breeders maintained in two different rearing systems. To achieve this goal, cages (Cs) and earthen ponds (EPs) were used as experimental systems to provide unsuitable and suitable conditions, respectively. The fish were maintained under the experimental conditions for 18 months.