Economic assessment data in agricultural systems at farm level require a substantial methodology in order to assure result reliability. This paper aims to evaluate the effectiveness of a participatory approach which is being used by the Brazilian Agricultural Research Corporation (Embrapa) in aquaculture. This methodology consists in gathering technical parameters, production costs and other economic information by means of panel method with producers. Variables are obtained through consensus among participants of the panel by using the criteria of the most frequent features practiced in farms (modal producer). Later, data is updated in a regular basis by calling input suppliers, fish farmers and wholesalers in order to analyze price variation. The information resulting is spread via newsletters on website and consists of: costs of production, analysis of economic viability (e.g. net margins, effective operative cost), inputs and fish price index. As positive aspects, the methodology shows a strong reliability of data because information is directly provided by a representative sample of producers. Moreover, data collection presents a low cost compared to individual visits to producers or to surveys method. Continuous updating of database and the high level of participation of producers are other assets of this methodology. Despite their effectiveness, the method presents some challenges as: (a) Heterogeneity of producer's profile and consequent difficulty in standardizing data; (b) Logistic requirements related to team travel and organization of panels; (c) Producer's mobilization in order to assure their participation on the panels.