Freshwater pond aquaculture is the prevailing fish culture system worldwide, especially in developing countries. Climate change outcomes and inadequate environmental practices challenge its sustainability. This study applies emergy synthesis to assess the environmental performance of freshwater pond aquaculture in Brazil, aiming to identify and propose practices towards sustainability. As a study model, nine semi-intensive lambari farms operating at three levels of management were evaluated: low (LC), moderate (MC) and high (HC) control. Results showed that the main inputs for LC were services (27-46%), feed (7-39%), and water (15-21%), while for the MC and HC farms, they were feed (35-49% and 17-48%, respectively) and services (33-39% and 26-36%, respectively). All farms required more than 60% of their emergy from purchased inputs, resulting in low emergy sustainability index (ESI = 0.1-0.5). Replacing animal protein and oil on diet composition by vegetal sources, using superficial water instead of springwater, increasing juvenile productivity, and controlling pond fertilization can lead all systems to higher efficiency and resilience, increasing sustainability.