Bovine testes meal contains natural testosterone hormone which plays a role in the process of male sex differentiation. Melastoma malabathricum L. or rose mrytle, karamunting (Indonesian) plant has bioactive compounds that can increase testosterone levels in male rats. This study was conducted to examine the use of bovine testes meal and karamunting leaves extract as an alternative source of hormones in the masculinization process in the Nile tilapia. This study used tilapia aged 5-10 days, reared in tanks with a stocking density of 1 fish/L. This study used a completely randomized design with 4 treatments and 3 replicates. The treatments consisted of a control (commercial feed only), P1 (70% bovine testes meal + 30% commercial feed with 1.5% karamunting leaf extract), P2 (50% bovine testes meal + 50% commercial feed with 1.5% karamunting leaf extract), and P3 (30% bovine testes meal + 70% commercial feed with 1.5% karamunting leaf extract). As a result, the percentage of males and absolute weight growth were observed with significantly different values, while the survival rate showed values not significantly different between treatments. The water quality parameters were maintained within the optimal range for tilapia fry: temperature at 27–28°C, pH 7.0, ammonia at 0.25mg/ L, and dissolved oxygen at 8.0mg/ L. The administration of bovine testicular meal and karamunting leaf extract can be used for the masculinization of tilapia.