Brazilian aquaculture is undergoing major transformations which have been changing the whole structure of this sector. Except for the shrimp farming industry - which for years already has a high technology production structure - the majority of the Brazilian aquaculture had been characterized for small producers and low level of technology. However, over last years the sector has witnessed rapid professionalization. This paper aims to evaluate the main changes in the Brazilian aquaculture and its effects on sector structure. Strong demand in Brazilian fish market has led the industry to show growth rates exceeding 10% per year. According to FAO, Brazil is among the top fifteen world aquaculture producers with a total production of 707.461 tones (2012). Such evolution, similarly to those observed in other animal chains in the country, like chicken and beef cattle, carries major changes in the production structure. The increase of technological intensification and large projects by the private sector are some examples. Most of this technological intensification has occurred in the tilapia sector which accounts about 50% of the Brazilian aquaculture production. Research conducted by Embrapa in the tilapia sector in Brazil identified a recent increase in the use of technologies in aquaculture. This includes technologies related to fingerling vaccination, genetic improvements, large volume cages, nutrition, automation in feeding and harvest. One of the consequences of these changes in production refers to the strengthening of capital concentration. This concentration is undergoing by merging of local producers, capitalization from investment funds and FDI (foreign direct investment).