This study was conducted to determine the best duration of hormone addition through the feed to induce the sex ratio of common carp strain Sinyonya. The study was using a completely randomized design with 5 different treatments namely A (control), B (30 days), C (35 days), D (40 days), and E (45 days) and each performed in 3 replications. The fish samples used in this study were a common carp strain Sinyonya larvae 5 days after hatching and still have the egg yolks. A total of 1.500 larvae of fish larvae were used. The fish larvae were given feed that had been mixed with 17a-methyltestosteron hormone. Feed was provided ad hormonal satiation at 5 times a day, (08.00, 10.00, 12.00, 14.00 and 16.00). The average percentage of the male fish with the highest value obtained in treatment C (35 days) is equal to 100.00±0.00. The result showed that the addition of 17a-methyltestosterone hormone on feed for 35 days and 40 days was the best treatment to improve the sex ratio of male of common carp strain Sinyonya.