The minimum dosage of 17-alpha-methyltestosterone, administered via a single silastic implant, that will induce testicular maturation in the striped mullet was found to be 5-mu-g/g body weight. A working dosage of 25-mu-g/g body weight is recommended for routine use. When administered with a single 10 mg crystalline 17-alpha-methyltestosterone implant, the working dosage was found to be effective for at least 9 months.