The experiment took place at a farm household located in Binh Thanh commune, Thanh Binh district, Dong Thap province. A total of 240 Dutch ducks, aged 3-13 weeks, were raised in a 2,000m² rice field, and the experiment consisted of 5 treatments: T4, T8, T12, T16, and T20 (corresponding to 4, 8, 12, 16, and 20 ducks for each 100m² rice field, respectively). The experiment was replicated 4 times, resulting in a total of 20 experimental units. All treatments were subjected to identical conditions and received the same basic diet throughout the 10-week trial period, involving ducks aged 3 to 13 weeks. The study's findings indicated that Ducks in the T16 and T20 treatments exhibited lower daily weight gain (DWG) compared to those in the T4, T8, and T12 treatments. The T4 treatment showed the most favorable feed conversion ratio (FCR), attributed to the fact that ducks found more feed in the field when the duck population was only 4. As the number of ducks in the treatment increased, the FCR also rose. The highest profits were observed in the T20, T16, and T12 treatments, with profits declining gradually, while the lowest profits were recorded in the T4 treatment. Raising Hoa Lan ducks, with a quantity of 12 ducks/100m² (or 120 ducks/1,000m²) on a rice field, resulted in high profits, along with favorable daily weight gain, FCR, and carcass quality.