Economic biomass from tilapia production in net cages on a rural property in southeastern Brazil

Technological advancements in fish farming have allowed for increased productivity and a consequent increase in fish production. However, increased system productivity does not always result in better profitability. Economic biomass calculates the point of maximum profit based on a relevant variable. Two distinct methods are proposed: an indirect one, where biomass and inputs are a function of time; and a direct one, where biomass is a function of the system's main input: the feed used. The economic biomass in the two methods showed different figures: 173.66 kg m⁻³ for the indirect method and 153.38 kg m⁻³ for the direct method. In the indirect method, more inputs vary over time than just the feed considered by the direct method; therefore, each method can be used depending on the situation in which economic biomass is to be evaluated. In cases where more information is available about the use of inputs and biomass, the indirect method may be more suitable. On the other hand, when only feed use data as a function of biomass is available, the direct method would be the most recommended.