The present study assessed the environmental performance of an integrated aquaponic system combining trout (Oncorhynchus mykiss) and lettuce (Lactuca sativa) production, under controlled greenhouse conditions in a semiarid northern Chile. A gate-to-gate Life Cycle Assessment (LCA) was applied to evaluate environmental indicators, including Water Use Efficiency (WUE), Specific Energy Consumption (SEC), Cumulative Energy Demand (CED), and Global Warming Potential (GWP), over a nine-month production cycle. Results indicate that lettuce exhibited consistently higher resource efficiency, with WUE values between 61 and 101 kg/m3 and SEC ranging from 145 to 255 MJ/kg, in agreement with reported data. Conversely, trout production showed greater variability, with WUE values in the interval between 18 and 36 kg/m3 and SEC ranging from 490 to 890 MJ/kg. Water intensity (WI) for trout increased throughout the cycle from 1.85 to 4.1 m3/kg. In contrast, lettuce WI remained low (1.0-1.3 m3/kg), as a result of stable evaporative and recirculatory conditions. GWP values ranged from 6.2 to 12.4 kg CO2-eq/kg for lettuce and 29.5-58.7 kg CO2-eq/kg for trout, largely due to electricity consumption and feed transport. These results confirm that the plant component of the aquaponic system is more environmentally efficient in terms of both water and energy use, while the fish component imposes higher environmental burdens like other intensive aquaculture systems. This study provides novel, empirical evidence supporting the environmental viability of coupled aquaponic systems and identifies critical hotspots for optimization, particularly in solid waste management, energy demand, and nutrient recovery.