||We used Life Cycle Assessment (LCA) to evaluate some of the environmental implications of using commercial versus artisanal feeds in Peruvian freshwater aquaculture of trout (Oncorhynchus mykiss), tilapia (Oreochromis spp.) and black pacu (Colossoma macropomum). Several scenarios believed to be representative of current Peruvian aquaculture practices were modelled, namely: production of trout in Andean lake cages; and culture of black pacu and tilapia in Amazonian and coastal lowland ponds, respectively. In general, Peruvian aquaculture is characterised by low technological intensity practices. Use of commercial aquafeeds is widespread, but artisanal feeds are frequently used in certain small-scale farms. We found that trout feeds feature higher environmental burdens than do black pacu and tilapia feeds. A similar trend is observed for production of these species. Across species, the substitution of artisanal with commercial feeds, despite improving feed conversion ratios in all cases, does not always reduce overall environmental impacts. This is due to the additional energy use and transportation requirements associated with commercial feed inputs. The substitution of artisanal feeds with commercial ones generally increases environmental impacts of the fish farming systems for the specific feeds considered, despite enhanced FCRs and economies of scale. This is due to the higher environmental impacts associated to certain feed inputs used in commercial feeds, in particular highly refined feed inputs. Consequently, in light of the importance of feeds to overall life cycle impacts of aquaculture production, the Peruvian aquafeed industry should preferentially source less refined and, in general, less environmentally burdened feed inputs (e. g. Bolivian soybean products over Brazilian, high quality over lower quality fishmeal, avoiding protein concentrates, etc.), to the extent that fish farming performance (i.e. feed conversion efficiency and cost structure) is not strongly affected. Among species, black pacu aquaculture shows the best environmental performance.