Effect of 17α-Methyl-Testosterone Hormone on Growth Performance, Feed Utilization, and Gonads Histology of Different Ages of the Nile Tilapia (Oreochromis niloticus)

Three different weights of the Nile tilapia (Oreochromis niloticus) were used in this study, namely 7.7g (T1), 18g (T2), and 26g (T3) to investigate the effects of the 17α-methyl-testosterone hormone (17a-MT) on the growth performance, feed utilization, and gonads histology. Varying concentrations of hormones were added based on the weight of the fish. Specifically, 6, 12, and 18 ml of 60mg of 17a-MT/ kg feed were administered to the respective weight groups. Control treatments (C1, C2, and C3) were also included for each weight category. The fish were provided with a commercially manufactured pellet feed containing 30% protein, 3% fat, and 4% fiber. This food was administered to the fish twice daily, with a quantity equivalent to 4% of their body weight. The fish density was subjected to a stocking strategy, where the sex ratio was maintained at a ratio of 1 male to 2 females for 12 weeks. The T3 group achieved a statistically higher significant survival rate and final body weight (P< 0.05). The  T2 and T3 groups exhibited the lowest recorded values of PPV, respectively. The ovaries of the fish in the control groups had a substantial quantity of mature vitellogenic oocytes (MVO). The testes of fish exhibited the presence of normal spermatogenic cells (SC) and demonstrated a typical process of spermatogenesis. The ovaries of fish that were administered 17α-methyl-testosterone hormones exhibited significant ovarian atrophy, characterized by the presence of severe atresia in several oocytes. While the testes of fish exhibited a moderate level of testicular degeneration characterized by degenerative alterations in the spermatogenic cells. The findings indicate that the hormone exhibits efficacy across various age and weight categories of fish. Therefore, hormonal treatment at these ages can be a means of controlling the ovulation process in tilapia fish.