The size dispersion in farmed fish has a strong impact on the bioeconomic performance of production, directly affecting the net profit. This work aimed to develop a bioeconomic model based on data from an experimental to identify optimal harvest time (OHT), considering market restrictions based on minimum marketable sizes (MMS). The commercial sizes analyzed were 350, 400, 450 y 500 g for a 6-month growth period. Two treatments were performed by pre-selecting the distribution in sizes for the first organisms for a heterogeneous (HT) and a homogeneous (HM) distribution. Fish form HT system were in a range for size of 44-155 g with an initial variance of 604.19 and a coefficient of variation (CV) of 25.5 %. The size range in HM was 87-112 g, with an initial variance of 34.91 and a CV of 5.9 %. The net benefits were more significant in the HM distribution than in the HT. The maximum gain in HT was obtained in the MMS = 350 g with an OHT of 196 days and a net profit of US $ 5,551.61, while the gain generated in 500 g was negative. The maximization of the net gain in HM indicated a higher profit of US $ 3,326.97 in 350 g with an OHT of 181 days. The MMS = 500 g had the lowest benefit (US $ 615.43) with an OHT of 221 days. The marketable biomass was 99.30% for HT and 99.53% for HM. HM revealed higher revenues of 10.66%. Sowing fish with a homogeneous size reduces the dispersion in growth and obtains higher profits. This model is a practical tool for aquaculture and represents a guide line for technical decisions that result in a higher net profit for the producer.